Only block keyup for keys where we have handled a keyup/press event

Fixes the issue of Vimium indiscriminately capturing keyup events,
introduced in PR #978.
Merge pull request #1130 from mrmr1993/fixKeyupCapture

Only block keyup for keys where we have handled a keyup/press event
Allow passing of keys to the underlying page.
Allow passing of keys to the underlying page (minor code review).
Allow passing of keys to the underlying page (more minor code review).
Allow passing of keys to the underlying page (populate page popup with existing rule).
Allow passing of keys to the underlying page (fix/maintain order of exclusion list).
Allow passing of keys to the underlying page (slight reformatting of page popup).
Allow passing of keys to the underlying page (comments can start with " too).
New icons for partially enabled, for passkeys.
Better state management for passkeys.
Better icon for passkeys.
Do not call handlers which do not exist.
Do not call handlers which do not exist (fixed).
Do not call handlers which do not exist (fixed, again).
PassKey tests (1)
Fix passKeys bug introduced in commit 700d35a
Merge pull request #1143 from smblott-github/passkeys

Passkeys: Pass some keys to the underlying web page without wholly disabling Vimium.
Confirm before restoring default settings
Merge pull request #1147 from mrmr1993/confirm_restore_to_defaults

Confirm before restoring default settings