New subplottool and various fixes

This pull request summarises three commits:

1) subplottool customized
    -) new subplottool, sliders are all vertially arranged, buttons for tight layout and reset (new files:  a ui file to compile formsubplottool.py using pyrcc)
    -) fix: subplottool is now modal dialog, was previously a QMainWindow, leaving the SPT open if one closed the plotwindow

2) function col2hex could not handle different color representations of mpl. Further the hexcodes in the dict COLORS did not correspond to the hexcodes for the default colors (quick workaround since default colors are defined somewhere else.)

I also change the labeling of untitled axes figureoptions dialog. 
Use the subplots_demo.py (at4 backend) to overview the changes.

![subplottool](https://f.cloud.github.com/assets/2571878/596154/6e3f3648-cb6a-11e2-8210-9257faeff68c.png)
![figureoptions](https://f.cloud.github.com/assets/2571878/596155/7615623e-cb6a-11e2-93d5-50020f0e1b2e.png)