CRG: use new Module API
CRG: support reset inversion
xilinx_ise/CRG_SE: reset inversion support
Added support for Altera Quartus (by Florent Kermarrec)
Added platform file for DE0 Nano (by Florent Kermarrec)
altera_quartus, de0nano: add copyright notices
New clock_domain API
MultiReg: remove idomain
generic_platform: do not create clock domains during Verilog conversion