Explain what the php_ignore_phpdoc does and allow the variable to exist but still turn on the feature.
Only match first, optional, identifier in doc tag

This follows up on #19 by matching only the first identifier, and only
if it occurs as the first or second argument and is preceded by at least
one whitespace character.
Merge pull request #25 from swekaj/option-refactoring

Document hidden option
Merge branch 'commonquail/match-first-tag-identifier'
Comments: Don't highlight whitespace as part of a match.

Improves on 'Only match first identifier in doc tag #24'
Save the 'iskeyword' setting before including the HTML syntax.

See https://github.com/pangloss/vim-javascript/issues/153
Add tags from StanAngeloff/php.vim/issues/28
Sort PHPDoc tags alphabetically, no functional changes.
Update PHPDoc with PSR proposed tags, closes #26.
Don't highlight {TRUE,FALSE,NULL} as constants.

See https://github.com/StanAngeloff/php.vim/issues/27#issuecomment-52159026
Add syntax overriding documentation.

Suggested by @Baldrs in #29. Closes #29, Php doc.