improve documentation, how to run and install, list of examples

[apgodshall]

I got it to run in Ubuntu, and in this change I ducument
general installation prerequisites, generally worded, as well
as a couple of apt-get and pip install examples to help
people get started and actually run this program instead
of getting frustrated and walking away.

[clolsonus]

Hi Tony, thanks for taking the time to look at MAdesigner and suggest some improvements. I have to apologize that I haven't been watching for (or expecting) pull requests and didn't see any github notification in my inbox, so your pr has been sitting idle for a year and I only noticed it now. I'm really sorry about that. In the last year I've made quite a few structural changes and have started to explore some FreeCAD integration (so the logical structure can be imported into CAD and further modified.)

Another thing I've explored is python egg packaging which messes up my example loading dialog box because examples are no longer a directory of files that can be navigated with a file browser dialog box. I'm not sure exactly how I'm going to handle that in the future, but I'll think of something. I now have the same issue to deal with for my airfoil loader dialog box.

If I can figure out how to reliably pluck 2d outlines off FreeCAD parts, then another thing I could explore is using FreeCAD solid modeling primitives to cut out stringers, lightening holes, etc. from ribs. That might be fun to explore someday.

Thanks again,

Curt.