CSS: Don't throw exceptions on HTTP URLs

Only call Directory.Exists() if it's actually a local path.
CSS: Fix image preview tooltips

Allow HTTPS images
Add better exception handling
Remove duplicated code
Use centralized relative path logic

Fixes #255
Helpers: Misc Project Path Fixes

Fixes #232 (GetRootFolder() for Installer projects)
Fix path methods for Miscellaneous Files with no solution open
CSS: Load image tooltips asynchronously

Also handles load failures correctly, and
shows image dimensions in base64 tooltips.
Code: Don't crash whenever you save a CS file

Don't assume that all CS / VB files
have nothing but methods.
Removed Chrome extension
Added Save as File from base64 html <img>
Code: Improve C# -> JS IntelliSense generation

Use an actual XML parser
Correctly XML-escape emitted descriptions
Misc cleanup
Use CodeModel to find attribute arguments
Code: Don't parse CS file unnecessarily
Fixed crashing issue with bad base64 syntax
Use ITextDocumentFactoryService to get ITextDocument instances

This changes the code which maps from ITextBuffer -> ITextDocument to
use ITextDocumentFactoryService instead of directly querying the
property bag.  Querying the property bag works but it's not truly
supported by the Visual Studio team and could be changed at any time.
The ITextDocumentFactoryService interface is the supported method for
getting ITextDocument values.
Fixed #266 by standardizing ignore folders
Fixed Markdown compiler issues
v1,4