Arrow keys messed up with line padding

When the bottom line padding is negative and the top line padding is positive (with a smaller absolute value) the arrow keys don't work as expected; up moves up two lines, and down doesn't work.

Steps to reproduce:
1. Set line_padding_bottom to -2
2. Set line_padding_top to 1
3. Press the up key
 a. Observe number of lines travelled
4. Press down key
 a. Observe nothing

Setting the padding like this was necessary as for some reason the font I used (TheMixMono, by LukasFonts) was offset from the baseline.