Support Typescript syntax.

[lijunle]

Resolve #46

• Make typescript as peer dependency.
• Add Typescript syntax support and unit test.

[codecov-io]

Current coverage is 96.29%

Merging #112 into master will decrease coverage by -0.66% as of cc53396

@@            master    #112   diff @@
======================================
  Files           19      20     +1
  Stmts          394     405    +11
  Branches        77      78     +1
  Methods          0       0       
======================================
+ Hit            382     390     +8
- Partial          7       8     +1
- Missed           5       7     +2

Review entire Coverage Diff as of cc53396

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