[MS 2.0 git f8d5642] Palette minimim width

MuseScore 2.0 commit f8d5642, Windows 8 64-bit

The Palette panel has a minimum width which is good, but some of the palettes need more room to show anything (at least on my large screen) when at min width. Key Signatures, Lines, Repeats and Text palettes are all blank. Key Sig only needs a bit more width to display properly, but the other three need quite a bit more width, esp when the vertical scroll bar is on.