New features:
- added buttons to buy several SUB or SHR chips at once
- on the welcome screen, added a small LED block indicating the series

Bug fixes:
- corrected the avialbility constraint for Margaret Hamilton
- corrected the layout for the "Reset all heroes?" dialogue
- fixed another small bug in the memory bank view

Miscellaneous:
- New hero colour for Sid Meier. Also changed some of the hero availability conditions (see game wiki)
