Pdf import and conversion

when importing a pdf MuseScore does not properly handle 8th notes silence or pauses.
It will always add up the silence to the next 8th note and generate a full quarter note space instead
this makes the tool rather useless.
The user has choose between the following options
- correct every bar where the error occurs by hand or
- not bother using the tool at all,
or as said before do it by hand by himself and not bother with the tool.