1) [input.lua] Pressing backspace while the cursor was at the beggining
of the text removed the first character. Fixed thanks to riidom.
2) [LÖVE 0.9] Use setLine(Width|Style) instead of setLine. Split
keyboard.pressed() into keyboard.pressed() and keyboard.textinput().
(see readme)
3) [utf8.lua] Add support for UTF-8 text editing. May still fail
spectacurlarly with invalid UTF-8 strings.
