* replaced DelayedImportModule by ExceptionOnGetAttr so that "freezesr" have more chances to detect we use matplotlib
* further refactored chart code
* maxticks can not be passed as a keyword argument
* some progress in passing kwargs to the plotting function (needs more work)
made bar sizes (dx, dy) overridable in barchart3d
- use Qt4 backend for matplotlib. It is slightly nicer and means we do not need to include Tk (we include Qt anyway for ViTables)
- more user-friendly error messages on missing optional dependencies
- close figures explicitly so that they don't accumulate (not needed with the Tk backend)
* downgrade ViTables to 2.0 because it is much easier to "freeze" (py2exe et al.)
* make PyQt4 optional
* change version number (0.8pre1)
fix warning message for 3D plots
fix setup script to include matplotlib & its "dependencies"
nicer message for "view" command
uncomment charts tests
updated INSTALL instruction for vitables & matplotlib
switch back to the Tk backend for matplotlib, instead of Qt because it does not work  when the python script is run
by nppexec in notepad++ (the window does not open)
style improvements
rm blank
add new shortcut in npp to launch vitables (bound to F9 by default)
more style fixes courtesy of PyCharm inspections
more style fixes courtesy of PyCharm inspections
update TODO
added stub for 0.8 changelog
nicer default colors