Improve parsing of modifier text with plus-symbols (#577)

Since quotes are not passed into GMT, it can be difficult to know if any combination of +letter is a modifier or not.  To eliminate as many cases as we can, we do this:
For argument to an option that takes modifiers, replace any + symbol that is not followed by one of the allowed modifier letters with ASCII 1.
New: THe second time we find a + followed by a valid modifier we know it cannot be a modifer since a modifier can only be given once.  So +tTitle+test will now handle the second +t sequence as plain text.
Bug: If a string ended in a plus then it got removed.

With these improvements we are less vulnerable to this problem and a few tests could be simplified and a few actually had text ending in double-pus-symbols to compensate for the loss of the last.  Ultimately, the only foolproof way to not have a +letter be interpreted as a modifier is to use the octal code for the plus: \053.

Author: PaulWessel

doc/scripts/func_F_iso+.sh

@@ -71,7 +71,7 @@ $AWK -f tt.awk tt.txt > tt.d
 gmt set PS_CHAR_ENCODING ISOLatin1+
 
 # First the uncoded ones
-gmt psxy -R0/9/2/32 -Jx0.345i/-0.21i -BN+tISOLatin1++ -P -K -Glightred -Y0.0 << EOF
+gmt psxy -R0/9/2/32 -Jx0.345i/-0.21i -BN+tISOLatin1+ -P -K -Glightred -Y0.0 << EOF
 >
 1	4
 2	4

doc/scripts/func_F_stand+.sh

@@ -71,7 +71,7 @@ $AWK -f tt.awk tt.txt > tt.d
 gmt set PS_CHAR_ENCODING Standard+
 
 # First mark uncoded entries
-gmt psxy -R0/9/2/32 -Jx0.345i/-0.21i -BN+tStandard++ -P -K -Glightred -Y0.0 << EOF
+gmt psxy -R0/9/2/32 -Jx0.345i/-0.21i -BN+tStandard+ -P -K -Glightred -Y0.0 << EOF
 >
 1	4
 2	4

src/gmt_init.c

@@ -3436,11 +3436,14 @@ GMT_LOCAL int gmtinit_parse4_B_option (struct GMT_CTRL *GMT, char *in) {
 /*! . */
 void gmt_handle5_plussign (struct GMT_CTRL *GMT, char *in, char *mods, unsigned way) {
 	/* Way = 0: replace any +<letter> with <letter> NOT in <mods> with ASCII 1<letter>
+	 *	    We only skip +<letter> the first time it is found (if in <mods>).
 	 * Way = 1: Replace ASCII 1 with + */
 	gmt_M_unused(GMT);
 	if (in == NULL || in[0] == '\0') return;	/* No string to check */
 	if (way == 0) {	/* Replace any +<letter> with <letter> NOT in <mods> with ASCII 1<letter> */
-		char *c = in;
+		size_t n = strlen (mods);
+		char *c = in, *p = NULL;
+		unsigned int *used = gmt_M_memory (GMT, NULL, n, unsigned int);
 		for ( ;; ) { /* Replace super-script escape sequence @+ with @1 */
 			c = strstr (c, "@+");
 			if (c == NULL) break;
@@ -3451,10 +3454,17 @@ void gmt_handle5_plussign (struct GMT_CTRL *GMT, char *in, char *mods, unsigned
 		for ( ;; ) { /* Now look for +<letter> */
 			c = strchr (c, '+');	/* Find next '+' */
 			if (c == NULL) break;	/* No more + found */
-			if (!strchr (mods, c[1])) /* Not one of the +<mods> cases so we can replace the + by 1 */
+			p = NULL;
+			if (c[1] && (p = strchr (mods, c[1]))) {	/* Any of ours */
+				unsigned int k = (p - mods);
+				if (used[k]) p = NULL;
+				else used[k]++;
+			}
+			if (!p) /* Not one of the +<mods> cases (or already fixed) so we can replace the + by 1 */
 				*c = 1;
 			++c;
 		}
+		gmt_M_free (GMT, used);
 	}
 	else /* way != 0: Replace single ASCII 1 with + */
 		gmt_strrepc (in, 1, '+');

test/psimage/transparent_gif.sh

@@ -10,14 +10,14 @@ ps=transparent_gif.ps
 gmt psbasemap -R0/1/0/1 -JX7c -Y19c -B+glightblue+t"no option" -K -P > $ps
 gmt psimage @warning.gif -Dx0.5c/0.5c+jBL+w6c -O -K >> $ps
 
-gmt psbasemap -Y-9c -R -J -B+glightblue+t"-Gblack\053t" -O -K >> $ps
+gmt psbasemap -Y-9c -R -J -B+glightblue+t"-Gblack+t" -O -K >> $ps
 gmt psimage @warning.gif -Gblack+t -Dx0.5c/0.5c+jBL+w6c -O -K >> $ps
 
-gmt psbasemap -X8c -R -J -B+glightblue+t"-Gwhite\053t" -O -K >> $ps
+gmt psbasemap -X8c -R -J -B+glightblue+t"-Gwhite+t" -O -K >> $ps
 gmt psimage @warning.gif -Gwhite+t -D0.5c/0.5c+jBL+w6c -O -K >> $ps
 
-gmt psbasemap -X-8c -Y-9c -R -J -B+glightblue+t"-Gred\053t" -O -K >> $ps
+gmt psbasemap -X-8c -Y-9c -R -J -B+glightblue+t"-Gred+t" -O -K >> $ps
 gmt psimage @warning.gif -Gred+t -Dx0.5c/0.5c+jBL+w6c -O -K >> $ps
 
-gmt psbasemap -X8c -R -J -B+glightblue+t"-Gblue\053t" -O -K >> $ps
+gmt psbasemap -X8c -R -J -B+glightblue+t"-Gblue+t" -O -K >> $ps
 gmt psimage @warning.gif -Gblue+t -Dx0.5c/0.5c+jBL+w6c -O >> $ps

test/psimage/transparent_png.sh

@@ -9,14 +9,14 @@ ps=transparent_png.ps
 gmt psbasemap -R0/1/0/1 -JX7c -Y19c -B+glightblue+t"no option" -K -P > $ps
 gmt psimage @warning.png -Dx0.5c/0.5c+jBL+w6c -O -K >> $ps
 
-gmt psbasemap -Y-9c -R -J -B+glightblue+t"-Gblack\053t" -O -K >> $ps
+gmt psbasemap -Y-9c -R -J -B+glightblue+t"-Gblack+t" -O -K >> $ps
 gmt psimage @warning.png -Gblack+t -Dx0.5c/0.5c+jBL+w6c -O -K >> $ps
 
-gmt psbasemap -X8c -R -J -B+glightblue+t"-Gwhite\053t" -O -K >> $ps
+gmt psbasemap -X8c -R -J -B+glightblue+t"-Gwhite+t" -O -K >> $ps
 gmt psimage @warning.png -Gwhite+t -Dx0.5c/0.5c+jBL+w6c -O -K >> $ps
 
-gmt psbasemap -X-8c -Y-9c -R -J -B+glightblue+t"-Gred\053t" -O -K >> $ps
+gmt psbasemap -X-8c -Y-9c -R -J -B+glightblue+t"-Gred+t" -O -K >> $ps
 gmt psimage @warning.png -Gred+t -Dx0.5c/0.5c+jBL+w6c -O -K >> $ps
 
-gmt psbasemap -X8c -R -J -B+glightblue+t"-Gblue\053t" -O -K >> $ps
+gmt psbasemap -X8c -R -J -B+glightblue+t"-Gblue+t" -O -K >> $ps
 gmt psimage @warning.png -Gblue+t -Dx0.5c/0.5c+jBL+w6c -O >> $ps