Theo fixes

[theogam02]

Fixed the toolbar going out of screen (issue #17). The sheet name that is displayed on the screen now has a maximum length and the rest is cut off and replaced with "...". This is a fix that should take care of small screen sizes such as my 13" laptop. A proposal for further work is to make the top menu resizable according to screen size.

[tomcl]

Adjustments to cropping of text to be done in future PR