adderall: Simplify the run and run* functions

Lifted some common code out, and moved it to adderall.internal instead.
Same functionality, shorter code, less copy & paste.

Signed-off-by: Gergely Nagy <algernon@madhouse-project.org>
adderall.dsl: Turn fresh into a macro, and spice it up

This changes the syntax of fresh: instead of returning an LVar or a list
of LVars, it can now also run goals. If called without goals, works as
before (but takes a list of symbols instead of a space separated
string). If called with goals, wraps them in allᵍ, while also
introducing the fresh vars.

Signed-off-by: Gergely Nagy <algernon@madhouse-project.org>
tests: Stylistic cleanup

Use the canonical function names everywhere.

Signed-off-by: Gergely Nagy <algernon@madhouse-project.org>
tests: fresh + let cleanup

Since fresh can return a list of LVars, we can use a single let block to
assign LVars to variables, instead of some copy & waste hackery.

Signed-off-by: Gergely Nagy <algernon@madhouse-project.org>