Adds benchmark test
Some further refactoring
Checks CHAR_TABLE before EXTENDED_ESCAPE on encode
Merge pull request #5 from yury/change-if-sort

Checks CHAR_TABLE before EXTENDED_ESCAPE on encode
Merge remote-tracking branch 'origin/refactor-further'

Conflicts:
	lib/gsm_encoder.rb
v0.1.5
Reuse string in encoding benchmarks