Renamed 6502 to 6500, to reflect family name used on datasheet.
Altered [cpudl].type.IntegerType to fail gracefully if an insufficient number of bits are available.
Made [cpudl].CpuTest able to check that bit sequences do not decode.
Added tests for 6500 and Z80 instructions which should not decode.
Added support for <cpu> and <feature> elements.
Corrected error in explicit or implicit <choice>, which was disregarding <require> and <priority> when there was only one type.
Added support for 65C00 family (but not yet for the R65C00).
Added support for R65C00 (RMB, SMB, BBR and BBS instructions).
Added support for W65C00S (WAI and STP instructions).