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
* remove the public SyntasticHighlightErrors() function
* shift the above code into s:HighlightErrors(). This is called
automatically if g:syntastic_enable_highlighting is set
* to get the highlight regex we just look for a function called
Syntastic_<filetype>_GetHighlightRegex
* to force this function to be called, each error item must have the
'force_highlight_callback' key set
This code has one important functional change: now errors are *always*
highlighted if possible whereas previously they were only highlighted if
a call to SyntasticHighlightErrors was made.
Many of the syntax checkers were setting the 'bufnr' key for each
error manually and one was setting 'text' if it didnt exist too.
Add the 'defaults' option to SyntasticMake to set default values in the
returned error list - it only sets values if they are empty.
