add ParseMode that connects to some existing parser libraries

[coord-e]

• template-haskell
• haskell-src-exts
• ghc-lib-parser
• ...and more?

also we should separate packages for each of them.

[coord-e]

depends on #8

[coord-e]

Implemented egison-pattern-src-haskell-mode and egison-pattern-src-th-mode.