Viewer - grid - rework settings to preset, update color picker

[user0]

XnViewMP 1.4.0
Windows10 (22H2), display resolution 3840x2160, dpi scale 150%

Viewer - Grid Settings
UI is outdated and not in line with other tools

Suggestion

grid_settings_dialog.png

Few things that could be changed:
a) rework 'Defined grids' section into 'Presets' to keep UI consistent across app.
b) remove this small old color palette and show standard full size color picker instead.




Example

• Photoshop
  grid_ps.png

• Gimp
  grid_gimp.png