Add controls for the garden screen

[Ensiss]

This PR adds some control to the garden screen:

• ESC, q, x: quit
• SPC, RET, PGDOWN: next page. If used at the last page, quits.
• BACKSPACE, PGUP: previous page
• j, DOWN: next line
• k, UP: previous line
• s: sort list, then alternate between ascending and descending order. The column used to sort is determined by the next key:
  • n, 1: name
  • a, 2: age
  • s, 3: score
  • d, 4: description
• f, /: filter/search items. This prompts for a regex and keeps lines containing the regex. If the regex is invalid, nothing is matched.

It also:

• fixes a few display bugs (prevents long lines from overflowing and integer score in the garden)
• generalizes the get_user_string function (can now be used for a dynamic character set instead of just alphanumeric) and fixes its redraw (used a static offset before)

[jifunks]

this is a great feature -making a small tweak:

• keybinds aren't explained, added to bottom sp/next | bksp/prev | s <col #>/sort | f/filter | q/quit

[jifunks]

just noticed sort is alphabetical for days (8d is showing up before 55d when sorting descending), could do some string manipulation to capture the integers and do a 4-way sort on that (lol this is literally an interview question i've had before)