change build process to install generated plugin documentation with cmake

Squashed commit of the following:

commit bb5a149044f3a0e4aa18258859dc9d1332d253d7
Merge: f2d264e c52d265
Author: Jarrad Whitaker <akdor1154@gmail.com>
Date:   Mon Jul 21 20:30:12 2014 +1000

    Merge branch 'cmakePluginDoc' of github.com:akdor1154/MuseScore into cmakePluginDoc

commit f2d264e353b40963098bead30f8fb34b9b152e54
Author: Jarrad Whitaker <akdor1154@gmail.com>
Date:   Mon Jul 21 20:22:48 2014 +1000

    revert a packaging change unrelated to this PR

commit 729147e912f9dd65029dec9de11519c71cad6eae
Author: Jarrad Whitaker <akdor1154@gmail.com>
Date:   Mon Jul 21 20:18:37 2014 +1000

    modify build process so plugin documentation is installed by cmake

commit e836b35df81e65cf78a87043747571cdd3e97fcc
Author: lasconic <lasconic@gmail.com>
Date:   Sat Jul 19 16:21:14 2014 +0200

    fix #27871 + more cosmetic changes to palettes

commit d881b20e1e97dfaf85ae3175f3556c5dbf6c7fdb
Author: lasconic <lasconic@gmail.com>
Date:   Sat Jul 19 12:29:20 2014 +0200

    set mscVersion to the current version after the first layout of 1.3 scores

commit c52d2652b023b521c1a17889da059c727d4737fb
Author: Jarrad Whitaker <akdor1154@gmail.com>
Date:   Mon Jul 21 20:18:37 2014 +1000

    modify build process so plugin documentation is installed by cmake

commit 4dd4a0d43cfe9859f79e5a03f3021f96d630a28c
Merge: b4d51ee 8cc66dd
Author: Jarrad Whitaker <akdor1154@gmail.com>
Date:   Mon Jul 21 13:48:43 2014 +1000

    Merge branch 'master' of git://github.com/MuseScore/MuseScore

commit b4d51ee2986181a4daad0e7109dfd7ddc68673c8
Author: Jarrad Whitaker <akdor1154@gmail.com>
Date:   Mon Jul 21 13:25:38 2014 +1000

    remove bad debdepends
fix indenting
Merge pull request #1052 from akdor1154/cmakeInstallPluginDoc

change build process to install generated plugin documentation with cmake