Add dtx format support

[mugabe]

Depends on bemusic/bms-js#28

Not sure about design.

Initialy I have an idea to pass file extension directly to format option, but it have possible issue with undefined matcher in bms module if the file with non bms/dtx extension passed.

So now here some smelling code to keep default behaviour.

[codecov-io]

Codecov Report

Merging #1 into master will increase coverage by 0.28%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master       #1      +/-   ##
==========================================
+ Coverage   97.37%   97.66%   +0.28%     
==========================================
  Files           8        8              
  Lines         267      300      +33     
==========================================
+ Hits          260      293      +33     
  Misses          7        7

Impacted Files	Coverage Δ
src/loader/BMSNotechartLoader.js	100% <100%> (ø)	⬆️
src/index.js	94.59% <100%> (+0.47%)	⬆️
src/loader/index.js	94.73% <100%> (+0.98%)	⬆️
test/notechart-test.js	100% <100%> (ø)	⬆️
test/loader-test.js	100% <100%> (ø)	⬆️

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[mugabe]

• Column generation added
  Columns are not ordered now, but as I see it does not make a sence for bemuse. Right?
  Column mapping options translated from playerOptions to bms-js.

• noShifting option for skip chart transformation added

• Updated ESLint dependencies
  Override ecmaVersion as async used

• DTX support covered by tests