Gmoccapy: Fix arrow key up/down bug in tooleditor

[Sigma1912]

The key_press handler inside 'tooledit_widget.py' interferes when using the arrow up/down keys (one keypress results in moving two rows ):

New (fixed) behavior:

[hansu]

But with this fix, this handy function wouldn't work any longer:

[Sigma1912]

Not sure I like it much.
Notice that this 'handy function' makes it impossible to move the cursor inside the cell left or right as it will automatically jump to cell beside it.

[Sigma1912]

Also when you hit enter to finish the edit it automatically goes into editing the cell below.

[Sigma1912]

What we could possibly do is retain the 'Tab' key function so we can go on editing the cell to right.

[Sigma1912]

Tab key enabled:

[gmoccapy]

I like Sigmas solution with the Tab key ;-)

[Sigma1912]

Demo with Tab and Esc keys:

[Sigma1912]

I'll put the Tab and Esc key feature in a separate PR against master as it is not a bug fix.