use versioned xcm

[xlc]

closes #624

Note: This is a transaction version breaking change and requires update of frontends.

[codecov-commenter]

Codecov Report

Merging #635 (eadd418) into master (ea0ddea) will decrease coverage by 0.03%.
The diff coverage is 62.90%.

@@            Coverage Diff             @@
##           master     #635      +/-   ##
==========================================
- Coverage   75.86%   75.82%   -0.04%     
==========================================
  Files          78       78              
  Lines        6479     6486       +7     
==========================================
+ Hits         4915     4918       +3     
- Misses       1564     1568       +4     

Impacted Files	Coverage Δ
xtokens/src/lib.rs	70.21% <17.85%> (-1.43%)	⬇️
xtokens/src/tests.rs	100.00% <100.00%> (ø)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update ea0ddea...eadd418. Read the comment docs.