crc: modify CRCChecker to remove CRC and clean up
xilinx_vivado: add parameters to pass specific commands (to be declared in platforms)
mibuild/xilinx_vivado: fix list aliasing problem
actorlib/structuring: remove PipeStb/PipeAck (PipeStb similar to Buffer and we can use a small fifo instead of PipeAck)
Merge branch 'master' of https://github.com/m-labs/migen

Conflicts:
	mibuild/xilinx_vivado.py