Packaging and substantive work re loading/reloading style sheets.
- All tests pass, and hand tests pass with both --gui=qt and --gui=qttabs, but perhaps caution may be advised.
- Corrected bugs that would cause crashers when --gui=qt.
- Created the StyleSheetManager class in qt_gui.py to handle all aspects of  Qt style sheets in Leo.
- Created LeoQtGui.reloadStyleSheets and LeoQtGui.setStyleSheets access methods.
  For example, the style-reload command now simply calls g.app.gui.reloadStyleSheets.
- SSM.munge now does a good job of approximating what Qt does, which makes stylesheet checks work.
- Added more useful tracing when checks fail.  This helped improved SSM.munge.

Leo build: 20140913084405