Augment vcs command (#161)

* Updating to keep up with Direction mega PR
Fix several classes to use ActualDirection/DataMirror.directionOf API
Fixed up Flip and UInt literal api references in several tests

* Provide new flags to allow modification of VCS command
New flag "--more-vcs-flags" to add additional flags to VCS command line
New flag "--more-vcs-c-flags" to add additional flags to CFLAGS portion of VCS command line
Provide simple test in ToolChainSpec to show command line construction
Refactored PeekPokeTesterUtils to make above test easier to implement