commitmonitor Code

* update to VS2013
* drop support for XP, now at least Vista is required
* patch apr to fix a linker error with the Windows 8.1 SDK

Update references to new website location.

installer: specify CompressionLevel="high" and replace single quotes with double quotes

Setup.wxs: minimum OS is Windows XP SP3

Setup.wxs: fix the path to the binaries

* add icon to the msi which is shown in the windows programs window
* install an url which points to the website in the start menu
* start CommitMonitor after the installation finishes. We do this without a checkbox but unconditionally because the checkbox of the WiX ExitDialog can't be modified, and since msi checkboxes are not transparent that checkbox looks plain ugly on our nice white background.

Closes issue #287

convert tabs to spaces.

(Closes issue #189) : Snarl notification
* register CM with snarl
* register three different notification classes

(Closes issue #152) : Use Snarl popups
* include the snarl API
* use snarl to show a popup if it is running, otherwise still use the CommitMonitor popup as usual
* include the png resource in the installer for snarl to use

(Closes issue #156) : Installer should remember previous install location
* save the install location in the registry and make the installer use it if available.