Added better built-in class support

Added a new global g:php_builtin_classes that holds class methods,
properites, constants, static methods and static properties in a
structured directory of directories.
This way we can be smarter on built in class instance
or static completions, and we can now include properties to the completions.
whitespace cleanups
Remove tags
more whitespace cleanup, remove old dictionary
Fix variable undefined variables and functions errors
fix modline noexpandtab
Add classes from tags into constant completion and g:php_keywords
Make smarter completionpopup values

When completing in static content variables should prefixed with $
Class constatns should be marked as kind: d
Add a closing parent after function prototypes for consistency with tags
Keyword matching don't have to be case sensitive
Add built-in classes when completing in no class context
Detect class for variables returned from static methods of built-in classes
Improve performance with precompiled built-in classname dictionary
Make function argument search pick up arguments when { is not on the same line

Fixes: #15
Merge branch 'issue15'