Fixing strange bug with general settings

General settings were always reverted for some reason at least
on sailfish. This commit renames general to gen which seems
to work for me.

This commit also changes updateversion.sh to take version number
by using `git describe`.
Clean-up and style changes

- Slightly better background color for menu
- Removed and ignored version.h
- Changed about window
version.h not needed
Show ThumbTerm as the name

As this is not essentially FingerTerm anymore the original
name shouldn't be used to advertise the product for now.
Names of binaries and other files shall remain.
Better url detection
Fixed .gitignore to ignore all build products.
Added .gitattributes to ensure correct normalization of line endings.
Unset POSIXLY_CORRECT on startup to get bash to behave correctly

e.g. to read its .bashrc file.
Changed default font color to bright green.
Don't wake up keyboard on arrow or Page Up / Page Down key press.
Made background transparent
Support for landscape mode
Maximized key sizes on virtual keyboard + reduced opacity of inactive keyboard to make it easier to read text obscured by keyboard.
Added a cover (code borrowed from tph's port to Silica made in the silica branch)
Added a README
README tweak
Larger pop-up key
Fixed bug that caused main window to retain portrait width when rotated to landscape.
Updated cover colors
Added Cover.qml to project file.