[REQ] Single-page mode

[gh658804]

It would be nice if there was a mode (in addition to what exists now) in which the user would see and edit everything in one page. At the left the list of strings would be shown (i.e. STR_ERROR_GAME_LOAD_FAILED, STR_ERROR_GAME_SAVE_FAILED, etc.) and when clicking on a string, all editing controls for it (textboxes, save button, etc) would appear on the right. With today's large screens with even larger resolutions, it could be feasible to see everything in one screen. Also in that mode, when saving, the list could remain in the last selected string, not be refreshed and force the user to start from the top again. This could be configurable (per user), he could just click on a button or combobox to select the screen mode.