Allow specifying initial SKELLY_NUM

[carlinigraphy]

To either source several different config files, or even source compiled conflang within conflang itself.
Passing a --initial-skelly allows for sequential runs to not stomp each other.

Maybe should also output the _SKELLY_NUM in a more friendly format.
_SKELLY_MAX?

Could do something like:

conflang --in file1.conf  --out file1.bash
conflang --in file2.conf  --out file2.bash  --initial-skelly "$_SKELLY_MAX"
source file{1,2}.bash