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
The js syntax checker was 4 checkers stuffed into 1 file. Now it is
broken down so that each checker is in its own file inside
syntax_checkers/javascript/ while syntax_checkers/javascript.vim just
determines which file to source.
Change the names of the global js checker config variables so that
they all start with "syntastic_javascript_". This is purely for
namespacing.
Remove some unneeded logic around the config variables too. Not sure how
it got in there, but it was more confusing than helpful without offering
any benefits...
