Added "kernel/yosys.h" and "kernel/yosys.cc"
Added CodingStyle document
Added "log_dump_val_worker(char *v)"
Added native support for shift operations to ezSAT
Using native ezSAT shift ops in satgen, fixed $shift and $shiftx SAT models
New techmap default rules for $shr $sshr $shl $sshl
Improvements in test_cell