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.
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.
List of regexps specifying files that should neither be checked, nor
included in error lists. The full paths of files are matched against
these regexps, and the matches are case sensitive.
We dont want to set the loc list by default since syntastic isnt the
only plugin using loclists - and we dont want to clobber other peoples
loclists.
This option allows the user to override this behaviour if it suits their
workflow.
This allows users to customize the coloring of Syntastic's signs, and
also provides them a way to highlight the entire line using :sign's
linehl feature. It preserves the current default behavior of using
the error and todo highlight groups if the customized ones aren't
present. If the linehl group doesn't exist, then it's the same as not
specifying one, so no special highlighting for the line will occur.
Update README -> FAQ to include an explicit question "How can I pass
additional arguments to a checker" and update to the vimdoc "Configuring
specific checkers" to point users to global variables accepted by
'syntastic#makeprg#build' before pointing them to checker source code.
* remove the changelog, credits and (outdated) doc on writing syntax
checkers
* doc the `syntastic#makeprg#build()` options
* doc how to select which syntax checkers to use
