Update nightly release script to not duplicate nightlies

Fix terminal emulator support

Improve command bar keybindings

The command bar now supports better keybindings:

CtrlA, CtrlLeft: start of line
CtrlE, CtrlRight: end of line
CtrlF, AltRight: next word
CtrlB, AltLeft: previous word
CtrlW, AltBackspace: delete previous word
CtrlV: Paste
Arrow keys as usual

These keybindings are not rebindable (maybe support will be added
in the future).

Replace home directory before performing SaveAs

Fixes zyedidia#820

Fix moving to end of line on cursor down

Update readme

install the snap with make (zyedidia#747)

* install the snap with make

* set the source-type to git, remove get

* remove extra space

Re-add literate supportg

Add option to disable use of a the primary clipboard

Closes zyedidia#544

Fix string width for different sized tabs

Fixes zyedidia#475