add option for controling the behaviour of explicit dependencies
long option for use explicit
move linker man page to makeflow_linker
add -e to man page
add -e to help display
make use_explicit a global option.

use_explicit was elevated to a global since it potentially affects every function.
allow explicit dependencies to be copied or skipped
add perl file type
list perl extensions
add usage message
check for perl extension
pass explicit dependency behavior to drivers
first stab at perl driver
include option in test
invoke perl driver for perl files
Add option to control behavior of linker when encountering explicit dependencies.

When `explicit` is enabled dependencies which are part of an explicit dependency (e.g. standard libraries) are skipped.
The goal is to make a smaller package which still represents the entire dependency tree.
Use of the explict flag requires the user to enforce the condition that the dependency is properly installed at each execution site.
handle perl files in package structure and build package
Driver for perl files.

The linker can now find and package perl dependencies.
recursively delete workspace if it exists
create workspace with random path to avoid conflicts