New font fixes and small UI fixes

[penfold42]

display_draw_str and char again support arbitrary scaling of fonts.

• if odd, scale the 8x6; if even scale the 16x12
• fixes my splash screen :)

ssd1306_draw_char_with_font() fix logic on preclearing background of character cell.

• if drawing black, clear with white
• if drawing white, clear with black
• if colour==2, do nothing so OR/XOR drawing works

16x12 font tweaks

• reformatted and labelled each row of data
• adjusted centering of 'f' 's' and 't'. "And then a (1px) step to the right"

fix draw_h_tick_marks() wrong Y offset on a couple of the ticks

Fix waterfall scrolling some crumbs down

[dawsonjon]

Thanks!