New variables: g:syntastic_debug_file, the name of a file where to write
debugging messages, in addition to adding them to the message history.
The old g:syntastic_debug is now a sum of flags:
* 1 - trace checker calls
* 2 - dump loclists
* 4 - trace notifiers
* 8 - trace autocommands
* 16 - dump syntastic variables (not implemented yet)
(1) Checkers now have an _exec attribute, and an accessor getExec().
(2) CreateAndRegisterChecker() initializes _exec from an optional argument
'exec'. If this argument is missing, 'name' is used instead.
(3) Functions SyntaxCheckers_*_IsAvailable() are now dictionary functions.
(4) Functions SyntaxCheckers_*_IsAvailable() are now optional. When
they are missing, they are assumed to return executable(expand(self.getExec())).
(5) Argument 'exe' of function syntastic#makeprg#build() is now optional.
If this argument is missing, expand(self.getExec()) is used to set checker
executables.
Make SyntaxCheckers_*_GetLocList() dictionary functions.
Pass a reference to the current checker to syntastic#makeprg#build().
Add an optional 'redirect' argument to CreateAndRegisterChecker().
Change the sh checker to use the new dictionary functions.
Add a new registry method getLocListRaw() (needed for the sh checker).
Older versions of Vim can crash if redraw is called while a popup is
visible. This commit adds a variable g:syntastic_delayed_redraws that
instructs syntastic to move redraws to a CursorHold / CursorHoldI
handler if redraw is called while pumvisible() is true.
It's now possible to deal with \0 characters in checkers' output.
Shell escaping is saner and safer.
SyntasticMake() has a new option 'preprocess'.
Checkers html/validator and eruby/ruby now use the new preprocess
option. Auxilliary script validator_decode.awk is no longer needed.
