massive PCB improvements / other changes

*increased width and height of layout by 2cm
*removed cue and tap buttons from layout. both functions can be mapped
on other buttons (5 hotcue buttons on each side for example)
*replaced move and loop button with tact switches
*removed play icon in layout (replaced with text)
*fader markings are updated to match new 10k faders. holes for screws
are also updated (1.5mm)
*hotcue PCBs now have 4 holes for screws instead of 3 (matched with
layout as well)
*massive improvements to main board (wiring should now be MUCH easier
since their number is greatly reduced)
*some fixes and changes to 6 pots PCB
*minor changes to top board for easier soldering
*updated readme to match button number
*updated circuit
*other small changes