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.
Normally composite types are handled by splitting them into simple
components, and applying the corresponding (simple) checkers. This
behaviour can now be disabled, by mapping composite types to a simple
ones.
