Make desktop enviroment names comparisons case insensitive
Make desktop enviroment names comparisons case insensitive

This is the follow up of commit 4cec687127adb1e96cc5b725eabe6a1188c4c873
by Alf Gaida <agaida@siduction.org>
detectDesktopEnviroment() returns uppercase, so we convert the user
supplied environment name to uppercase.

Signed-off-by: Luís Pereira <95d1463b1ff9eef535e39fb0d755bc242cfcea61@gmail.com>

lxde/libqtxdg,DrTobe/libqtxdg,libqtxdg/libqtxdg,libqtxdg/libqtxdg,DrTobe/libqtxdg,lxde/libqtxdg,DrTobe/libqtxdg,luis-pereira/libqtxdg,luis-pereira/libqtxdg