pfSense

Add install_freebsd.sh and use it

Add build_freebsd.sh and start using it

Remove outdated XXX message

Add git_checkout.sh and common.subr

This is the first of a set commits to start replacing big
builder_common.sh by smaller and specific scripts to do necessary build
tasks.

First is git_checkout.sh, a script used to checkout or update a git
repository on desired destination dir and branch or tag.

Remove script used during bootstrap conversion

Fix pkg repo name for tags

Remove stray 'i'

Fix variable name

Remove immutable flag before delete directory

Make sure licenses dir is removed to avoid duplicate it in the wrong package