style: fix warnings, make a few parsers applicative

-- Warnings Fixed

* "do-notation statement discarded a result": apply `void`
* parameter inferred as Integer: add type signature to multi_byte
* name shadowing for `scheme`
* remove tabs from test suite
* removed unused functions/module imports
    * traceShow
    * traceVal
    * alphaNumChar
    * genDelims
    * testURIReference
    * testDefaultUserInfoMap
    * import Debug.Trace

-- Applicative Parsing

* escaped
* subDelims
* unreservedChar