Cleanup.  Deprecate a number of checker variables.

New / refactored deprecation logging functions:
syntastic#log#oneTimeWarn() and syntastic#log#deprecationWarn().
Bug fix: refresh notifiers in BufEnter, rather than BufWinEnter.
Error highlighting cleanup.
Manual: add a note about netrw.
Make syntastic#util#parseShebang() aware of /usr/bin/env.
New option for SyntasticMake(): env.

Setting environment variables by prefixing commands with 'VARIABLE=value'
doesn't work under csh.  Solution: let Vim set the environment variables.
Vimlint: add g:syntastic_vimlint_options.
README: nit pick about re-enabling the perl checker.
Refresh optimisations.
Don't check compressed files.
New redirect checker for arduino: avrgcc.