This patch adds an option 'postprocess' to SyntasticMake(). The value
of this option is a list of names. Each name is translated to a
function syntastic#postprocess#name(). These functions are applied in
order to the list of errors just before SyntasticMake() returns. They
take a single parameter, the list of errors, and are supposed to
returned the processed list.
Make all the easy updates. There are still quite a few to do, but in
doing these ones I can see that syntastic#makeprg#build() needs to
accept a few more options. Namely:
* "postargs" that appear after the filename
* "tail" that appears after everything - used for things like
redirecting output and piping to grep/sed/etc
* the filename itself - only the java checkers needed this since they
specify the directory of the file to check as well
There are still a few other things to do as well:
* remove the options from the checkers that are now provided by
syntastic#makeprg#build implicitly - i.e. the checker exe and args.
* also, we need to doc the above implicit checker options
Since we're only using ghc to check and lint the file and not actually create output, we can pass -fno-code which omits code generation and speeds up the check quite a bit.
