create debugging branch

there are lots of bugs to fix.
Create a file with known bugs.
fix left and right

make LEFT and RIGHT go one character in the appropriate.
Unable to test with line wrapping as ENTER does not work yet.
Also fix some other bugs.
stop session spam

Remove session file from index and ignore any future .vim files.
fix delete

Pressing DELETE will now work properly and also not segfault.
report backspace bug
refactor Buffer::Changeset

Now contains topmost and bottommost ever lines.
Complete refactor of how they are combined. Now is only for 'adjacent' changesets.
Moves elements from other changeset to destination.
Much faster than copying, but invalidates amalgamated changeset.

Also fix backspace bug in the process.
fix enter

Now I can test line wrapping.
add support for keypad enter

... I think. I can't actaully test this yet.
report bug with ENTER

And remove old bug that was fixed.
fix enter

Also report an error with end.
fix end

Also report an error with LEFT
fix left

Also report bug with down and up.
Also ignore executables.