feat: Optionally allow selecting segment with a single click

[miurahr]

Pull request type

• Feature enhancement -> [enhancement]

Which ticket is resolved?

• Option to move to segment via single click
• https://sourceforge.net/p/omegat/feature-requests/1496/

What does this PR change?

• Add Preference.SINGLE_CLICK_SEGMENT_ACTIVATION
• Add checkbox for controlling single-click-activation of segments
• Make single-click activation of segments depends on cursor-lock-mode
• Allow single click to activate segment
• Single click moves cursor to the word pointed

Other information

TODO

• [ ] Update user manual
• [ ] Add unit test