Add semi-functional stub for completion extension

This change includes the beginnings of a completion extension.
The code is quite messy at this point but provides a starting point
for proper code completion.

At present, only a subset of Cobra keywords are provided and all
namespaces for the types contained in referenced assemblies (following
a 'use' statement).

Remaining work include finding a node from a given region and then
including the completion data from that node (e.g. class members).
Use 'cobra -path' as a more reliable way to find Cobra.Compiler.dll

This change also reverts the Gui project being built in
the 'Release' configuration and the CobraBinding also
outputting to 'Release' but not using the '-turbo' option.

They are now both back to 'Debug' configurations.
Merge latest changes from 'master'
Remove commented code from completion extension
Remove Cobra libraries from refs folder
Remove unecessary code to prevent compiler warnings
Add a TypeSystem.Visitor class
Add TypeSystem.ParsedCobraDocument class
Correct doc string typo
Add some semblance of working code completion!!!

This provides a good starting point for usable code completion.  Much work remains
in terms of proper architecure and general cleanup but it's the best attempt so far.
Make icon variables shared to the CompletionTextEditorExtension class
Remove commented-out trace statement
Lots of cleanup for code completion extension.

Regression introduced: Namespaces from references are no longer
proposed when typing "use"

New behavior: The "." character is no longer considered part of the
completion text.
Add support for completion of local vars/parameters
Support for more local variables and some types from project references

This code digs into the various BlockStmts contained by method statements
to make the variables declared in those blocks available to code completion.

This does not take into account variable scope...yet.

Additionally, lines of text ending in ' as ' will now provide all Type
names from project references as completion proposals.
Merge branch 'master' into completion
Minor update to README.md

Note that limited code completion is now supported and also do not
explicitly note that 64-bit Windows 7 has an issue since Windows 8
is also affected.
Include types from implicitly used namespaces and refactor a bit
Update minimum Cobra version required
Populate addonValue dictionary of node with its DomRegion

This dictionary is currently unused but I don't want to lose this
change as I will be creating a new branch to implement a new
CompilerManager class and will be using this branch as the starting
point.