Registry cleanup, stage 1.

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).
Registry cleanup, stage 2.

(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.
Registry cleanup, stage 3.

Make syntastic#makeprg#build() a dictionary function.
Remove the mandatory checker argument to syntastic#makeprg#build().
Update for shellcheck.
Merge branch 'master' into registry_cleanup
Update scss_lint to the new registry framework.
Cleanup.
Safety checks for ghc-mod.
Add a warning about using syntastic_delayed_redraws.
Merge branch 'master' into registry_cleanup
Merge branch 'master' into registry_cleanup
Jshint: really fix column handling in errorformat this time. ;)
Merge branch 'master' into registry_cleanup
JS-YAML: fix errorformat.
JS-YAML: fix errorformat.
placeholder should only be on input elements
Allow more HTML5 input types

This allows the following:

- search
- number
- range
- date
- etc

Somebody could in theory put type="foo", but all browsers' default input type is "text" and they all ignore unknown types.
Merge pull request #852 from kaleb/patch-2

html/tidy: Allow more HTML5 input types
Merge pull request #851 from kaleb/patch-1

html/tidy: placeholder attribute should only be on input elements
Merge branch 'master' into registry_cleanup