Revisions to dependency versions and README, and added back CMakeLists.txt for testing

Author: Adam Blake

README.md

@@ -33,7 +33,7 @@ make
 If all runs successfully, you should have an executable.
 
 #### Linux
-[Note: 'make install' is broken at the moment. Just copy the binary 'projectMSDL' to your choice of run-path. E.g.]
+[Note: 'make install' is unimplemented at the moment. Just copy the binary 'projectMSDL' to your choice of run-path. E.g.]
 ```shell
 cp src/projectMSDL ~/bin
 ```

dependencies_check.cmake

@@ -1,5 +1,5 @@
-if(projectM4_VERSION VERSION_LESS 3.1.13)
-    message(FATAL_ERROR "libprojectM version 3.13 or higher is required. Version found: ${projectM4_VERSION}.")
+if(projectM4_VERSION VERSION_LESS 4.0.0)
+    message(FATAL_ERROR "libprojectM version 4.0.0 or higher is required. Version found: ${projectM4_VERSION}.")
 endif()
 
 if(SDL2_VERSION VERSION_LESS 2.0.5)