build: fix problem with earlier cleanup

I really need to get rid of this
Moving towards stdlib for most assertion types

system-level things like dir, symlink, file, etc will be "core"

package- or platform-level things will be either stdlib or contrib
put system-level assertions in core

well maybe core is debatable.
bork_script_dir
use & ok

Probably the biggest change to bork since its inception.  It's all about "less
magic" while still retaining something of a DSL.
update readme
standardize on BORK_x_DIR variables in uppercase
stdlib, make "DI" command replacement actually work
big cleanup surrounding USE and OK
git: echo conflict messages
github: bringing it back
make: remove obsolete tasks
use: take relative paths for types
get rid of stdlib, everything is core
use -> register

register handles local paths only, takes priority over core
Merge branch 'use'

This is the biggest change to bork since its inception, basically assertions go
from "brew foo" to "ok brew foo"

It removes a lot of the magic around making the former style, while retaining
the bluntness that drew me to using bash for this to begin with.