modify hint_prefix to support multiple icons

[spflaumer]

hint_prefix now optionally supports three icons:

• above: when the hint is shown on the line above
• current: when the hint is shown on the current line
• below: when the hint is shown on the line below

a few if statements were also rewritten to be more compact

example screenshots: above: current: below:

[spflaumer]

i think i'm going to redo this pr

the quality is pretty low