Better dollar quoted strings, more keywords and types supported

Further improved the dollar quoted strings (see #8 for more details and examples with screenshots).
Added support for more keywords and types (see #7 for more details and examples with screenshots).
Identifiers, created inside functions are also recognized (see #3).

All the credit goes to Dominik (@dgehlich), as he was the one to contribute all of the above.

Better support for dollar quoted strings

Better support for dollar quoted strings.
Whitespace comments and more can follow the dollar quoted string (function body).

Add some missing keywords for date/time features

Add some missing keywords for date/time features.

Update syntax file according to 9.5 documentation

1.0.3

Update syntax according to PostgreSQL 9.5 docs

Update syntax file according to 9.4 documentation

1.0.2

Update syntax according to PostgreSQL 9.4 docs