[1.0] and [trunk] Max tempo speed limited to 400

The maximum value which can be entered in the Tempo speed field of the Tempo Properties dlg box is limited to 400.

This is not enough for early music pieces in which the semibrevis or the brevis -- and sometime the dotted brevis -- is the tactus.

This is a limit of the dialogue box only: manually changing the value in the .mscx file works (I tested tempo up to 720 without any side effect I could notice) but is outside the reach of most users.

The max value should be increased to 999 at least.

The change would not affect translation, documentation or feature lists.

Thanks,

M.