Revert "show explanation on failed snippet name validation"

This reverts commit a414f42a.

The code uses a KDE 4.7 class (kmessagewidget.h) and hence kdevplatform
fails to build on KDE 4.6 and older. Since KDevPlatform is supposed to
build against KDE 4.5 a solution without that widget needs to be found.

CCMAIL: kdevelop-devel@kdevelop.org
CCMAIL: gmary@lunacymaze.org