The big PKGBUILD cleanup

Hi,

Here it is, a refactor of all the MATE PKGBUILDs for Arch Linux.

In short, the complete MATE package tree now builds on Arch Linux i686 and x86_64. I've tried to fix everything I can, that said the Invest applet is still borked. I know this is a pretty huge pull-request but I srongly recommend that it gets merged ASAP because it definitely fixes a lot of stuff and will make maintaining these packages alot easier.

I've created an Arch repo hosting my packages so you can upgrade or install from scrath, both have worked fine for me. Add the following to `/etc/pacman .conf`.

    [mate]
    SigLevel = Optional TrustAll
    Server = http://mate.flexion.org/1.6/$arch

The long version.

  * The `depends` and `makedepends` are consistent with stefano-k's Debian packages.
  * The `autogen.sh` and `configure` options are consistent with stefano-k's Debian packages.
  * As a result of the two items above there is more feature enablment in these revised packages.
  * Build system is fixed. Thanks in part to `mate-common` 1.6.2 but I have also fixed the the broken `sed` in the `mate-common` PKGBUILD should we need it again in the future.
  * `libexec` is correct for the package which require it.
  * `python2` is now correctly referenced and used everywhere.
  * Pulseaudio is enabled in `mate-media` and `mate-settings-daemon`.
  * Indicator applet works, if that important to you.
  * All the `.install` files have been fixed up.
  * Simplified the PKGBUILDs as much as possible and removed "hacks" that are no longer required.
  * Replaced `sha256sums` and `md5sums` with the upsteam `sha1sums`.
  * All the packages build.

Finally, many thanks to:

  * infirit and stefano-k on the `#mate-dev` IRC channel for their help and patience over the last week.
  * Xpander69 for his understanding with all my pull-requests and prompt merging.

Regards, Martin.