#19455 Entering float numbers in EditTools

Stops continuous reformatting of float data entered in EditTools widgets.

Implemented adding a flag to the EditTools class which skips re-setting the  X and Y values if the edit originates from within the EditTools itself. Very similar to https://github.com/musescore/MuseScore/pull/181 .

See http://musescore.org/en/node/19455 for details and a discussion.