Use document fragment when adding multiple lines during update
Initial implementation of scrolling flickr fix. Has some issues marked by TODOs in the code.
Change selection drawing.

Selection is drawn as highlight rectangles behind the text. There are at most three rectangles drawn - one for the first partial line, one for the last partial line, and one for the block of lines in between. Selection is now true block selection, where the highlight extends to the right edge of the window.
Fixed flickering on page down
Added mousewheel support for Chrome. Needs testing on other browsers, and horizontal scrolling is wonky in Brackets at the moment.
Merge branch 'block-selection-drawing' into scrollfix
Code cleanup
Restore some code removed in a previous commit. This fixes long drag selection.
Merge branch 'block-selection-drawing' into scrollfix
Make selection drawing work with wrapped lines.
Merge pull request #1 from adobe/block-selection-drawing

Change selection drawing. - reviewed by nj
Merge remote-tracking branch 'origin/master' into scrollfix
Removed TODO for issue fixed in main app
Removed temp testing code from demo/theme.html
Change selection and text div layering.

Don't use z-index on the selection div since that places the div behind *everything* on the page that doesn't have a z-index. A better fix is to set position:relative on the text div, making sure it is in front of the selection div.
Minor code cleanup.
Attempting to fix Firefox; making horizontal scroll handling be an explicit redispatch
Merge pull request #2 from adobe/block-selection-drawing

Change selection and text div layering.
Merge branch 'master' into scrollfix
Switched to manually handling wheel events as opposed to trying to forward them to the scrollbar.