refac: Moved RP4 out of IO section to top-level sheet, as it's not really IO specific. Also fixed a bus connectivity issue with RP4 reported by ERC

schematic revision/issue-date bump to 0.2/2019-08-11

Added missing R51 pull-up on R/W in cartridge expansion section

Added missing pull-ups on /IRQ and /DMA in cartridge expansion section (part of missing RP4 resistor network)

Added missing pull-ups on /EXROM and /GAME in cartridge expansion section (part of missing RP4 resistor network)

checked all ICs in KiCad schematic BOM against Service Manual Parts List

Added missing resistors R43, R44, R45 (pull-ups on /LORAM, /HIRAM and /CHAREN outputs from CPU P0-P2

Checked all board caps (except RF modulator) in BOM against Service Manual parts list, and added type, voltage ratings and tolerance information from parts list to them

Added PWR_FLAGs to get rid of a number of ERC failures

main schematic (all but RF modulator) complete