Quoting option arguments by default

Tool pkg-config interprets quoting when processing .pc file and printing
query results. Internally it uses g_shell_unquote() from Glib for this.

It doesn't make sense to force quoting by the Template data type,
because one would wan't to be able to define more then one option in one
template. What makes sense is to quote option argument when one knowns
its an option argument. Therefore some combinators that construct
command line options do so now. To be precise its:

  includes :: [PkgTemplate] -> PkgTemplate
  libraryPath :: [PkgTemplate] -> PkgTemplate

In addition new combinators were introduced, to simplify this quoting
business:

  quote :: PkgTemplate -> PkgTemplate
  option :: Strict.Text -> PkgTemplate -> PkgTemplate
  strOption :: String -> PkgTemplate -> PkgTemplate

Function "quote" does the obvious thing of putting quotation characters
on the both sides of PkgTemplate. Functions "option" and "strOption"
construct new template from option (e.g. -I, -L, etc.) and its argument.
They use "quote" to append option argument.