Don't shadow Alt-Left/-Right in Linux keymap

The Alt-Left and Alt-Right shortcuts are used for inter-word jumps. I had to grep through all the keymap files to figure out why suddenly my Alt key wasn't working anymore ;)

Suggestions: Comment out the lines in the Linux keymap file, like this Mac issue: #42.

Open the Linux keymap file and compare its Alt-Left and Alt-Right entries with the approach described in issue #42. Confirm which lines define these shortcuts, then verify that the Linux keymap no longer shadows the inter-word jump shortcuts.

Written by the indexing model from the issue text.