Nemiver updates: fix warnings, small UI enhancements, etc.

[<shane shaneharper net>]

Hi.

I've pushed some "small" changes to a Nemiver fork I made on github (https://github.com/shaneharper/nemiver).

Here is a summary of the commit log:

    Don't list "<built-in>" in Open Source File window

    Polish code

    Open Source window: Double-click/Enter opens file

    Correct spelling in comments and log messages.

    "polish" test code (minor update)

    Improve layout of Set Breakpoint dialog

    UI selection widgets expand to use available space

    Add .gitignore

    Fix glade 3 warnings

    Fix compiler error and warnings (clang v3.4)

I hope these changes could be of use to others.

Nemiver has helped me debug code and I've found the Nemiver source code to be in very good shape!

Shane