Bugfixes and improvements

Improved: Text editor disabled while asynchronous context action
execution
Bugfix: Package is validated correctly when referencing function which
doesn't exist in the package
Bugfix: Navigate to definition works properly with common table
expressions
Bugfix: Queries starting with common table expressions are resolved
correctly to return data sets
Added: Better support for data type grammar resolution, e. g.,
TIMESTAMP(<n>) [WITH TIME ZONE], VARCHAR2(<n> [BYTE/CHAR])