fhdl: support inverted clock ports in instances
fhdl: support expressions in instance ports
fhdl: fix instance get_io
flow/actorlib: Simple Processor Interface (WIP)
actorlib/spi: fix memory port we/wd
bank: support for atomic writes
bank: remove RE signal for field registers
actorlib/spi/collector: atomic update for write_count
actorlib/spi: SingleGenerator
transform: unroll
transform/unroll: support for variables
transform/unroll: support empty dictionaries
transform/unroll_sync: support generator function
transform/unroll_sync: autodetect in/out
actorlib/spi: typo
bank/description: regprefix
pytholite: transformable elements
pytholite: visit AST and list registers
fhdl/structure: make all values hashable
pytholite: do not use ast.NodeVisitor