intellisense improvements, and bracket auto delete

auto delete is only in forward direction for brackets.

implemented an extension function to find bracket in backwards
direction.
Added bracket match highlighting, line numbers

Fixed bracket deleting also.
Added a status bar showing cursor position.
bracket deleting at beginning of file.
Added ability to get completion contexts from

clang sharp.
C++ intellisense.

Now intellisense and compleiton advice copes with C++, function
overrides, etc.
Code completion advice minor fix.
Partially implemented error link throughs.
Disabled bracket highlighting for ' and "

its doesnt make sense or work properly for these chars. Auto insert of
matching ' and " still work.
Error list link throughs now work