Enable tabs on the project file.
PBGitLane can be used from multiple threads. This means using a static variable isn't safe. Added a _laneIndex ivar to PBGitGrapher to prevent multiple instances of PBGitGrapher from interfering with each other.
Better handling of thread cancelation. Fixes pressing command-R rapidly in the history view and sometimes having no commits show.
Other Fix for #310

Fix for #310.
```
  ...
  message = "TypeError: 'undefined' is not an object (evaluating 'ns[ n[i] ].rows.push')";
  sourceURL = "file:///Applications/GitX.app/Contents/Resources/html/lib/diffHighlighter.js";
```

I turns out that the `inlinediff.diff()` method had issues caused by the use of Objects as HashMap. That's why @dgreensp added a fix using `Object.prototype.hasOwnProperty` (see #320). However this solution still fails when the key becomes `"__proto__"`, for some reason.

A simpler, saver and yet more efficient fix to the root issue is to just prefix the keys. e.g. `'"' + key`.
Remove unused icons and ensure template icons
Use NSImageCell for rendering sidebar effect

This removes need for own rendered highlighted sidebar icon.
Resolution independent PDF icons (with SVG source)

This is replacement for icons by Alexis Hildebrandt. I tried to be close as
possible to Alexis design, however there are following changes:

(1) Icons are now PDF, no need for @2x version, less files
(2) SVG source, instead Pixelmator which is proprietary paid software
(3) Icons are pixel aligned to non-Retina pixel boundaries (look sharp)
(4) Folder & remote (cloud) look are more inline with OSX default icons
SVG scale independent log (WebKit based) icons

Also removed old Acorn sources and Pixelmator sources. Icons were made to
preserve style of previous ones. No need for source as icons are SVG.
Pixel aligned PDF file icons (13 px height)
Provide a "User Cancelled" error so we don't crash when canceling "New".

Closes #275, #220.
add links to top in history and file view
Merge pull request #332 from ksuther/threading-fixes

Threading fixes for minor UI glitches
Start straightening up rev list
Add pull request #332 to the change log
Merge branch 'patch/fix-sidebar-template-icons' of github.com:nanoant/gitx into nanoant-patch/fix-sidebar-template-icons
Add pull request #280 to the change log
Merge pull request #333 from muhqu/patch-1

Other Fix for #310
Add pull request #333 (issue #310) to the change log
Merge branch 'crash-on-new-repo' of github.com:tiennou/gitx into tiennou-crash-on-new-repo

Conflicts:
	Classes/git/PBGitGrapher.mm
	Classes/git/PBGitLane.h
Check that the error pointer is non-nil before writing