Unify keyboard navigation in all modes

[dmik]

Currently, there are several mismatches, e.g.:

• Ctrl-PgUp/PgDn scroll in Normal mode and go to the first/last page in Fullscreen mode.
• No keys to go to the first/last page in non-Fullscreen mode at all.
• Home/End scroll horizontally to the left-most/right-most position while it would be more natural to go to the first/last page (as in many other apps).
• etc.

[pirx]

We should definitely use the left/right arrow keys (in addition to -/+) for previous/next page in presentation-mode (formerly fullsreen). This would make navigation much easier.

[Silvan Scherrer]

i 100% agree with this, as i missed them already. +/- works of course, but left/rifgt arrow is more intuitive.

[dmik]

(In [408]) Unified keyboard navigation in all modes (fixes ticket:177).

[dmik]

The shortcut now work as follows (the same for all modes):

• Home/End scroll to the top of the first / bottom of the last page.
• PgUp/PgDown scroll to the previous/next page (may not match the top of the page in continuous mode).
• Ctrl+Home/Ctrl+End go to the top of the first/last page.
• Ctrl+PgUp/Ctrl+PgDown go to the top of the previous/next page (same as -/+).
• Left/Right/Up/Down scroll the page to the corresponding direction.
• Ctrl+Left/Ctrl+Right scroll to the leftmost/rightmost edge of the page.
• Ctrl+Up/Ctrl+Down scroll to the top/bottom edge of the page.