Add new "phpDocTag" synIDName.

This name seems to be 7.4 runtime files addition:
https://gitorious.org/jasonwoof/vim-syntax/commit/fb8f7a4e5fa471649ee36e0021fb2966550bba48
Add support for array typed docblock classes

If you have an array of class instances, you can type ClassName[] in in the
docblock type field and have the plugin pick up the correct type when
indexing that array.
Merge branch 'array_support'
Added support for parent keyword
Improve array handling

Moved the de-arrayification of types into GetCallChainReturnType() with
the exception of the "foreach()" context. Some of the previously false
positive tests have been fixed for the array support and expanded uppon.
Improved code parsing

A standalone ! should indicate instruction boundary.
Made the array matching more strict, now it won't match []-s in parameters
of callchain item
Make code parsing more robust

Unified the operator handling inside GetCurrentInstruction().
Added square bracket handling inside GetCurrentInstruction().
Made recursive GetClassName() calls avoid getting into infinite loops
on lines without semicolons.
Make GetCurrentInstruction() recognize '::' as one token
Make built-in class more case insensitive

The built-in classes should be indexed and matched by regardeless of case
since php itself doesn't care for it. This helps class detection.
Make interface detection pick up the "interface" word in class titles

This catches two interfaces that previously was filed as classes.