Revert "Library defs don't bind to each other; fix #479"

This reverts commit 6b6e3f42627f360cbbad2287968b2a209ab43593.  It was
the wrong fix.
Fix manual example for `endswith`.
Lib defs don't bind to each other; fix #479 again
Add regression test for #479
Merge pull request #482 from mbruggmann/manual-fixes

Fix manual example for `endswith`.
Added library system with -l, -L, and JQ_LIBRARY_PATH
Handle a few edge cases, better error handling.
Fixing error messages.
Better bounds checking, proper handling of missing $HOME

Created util.[ch] to hold common utilities.
Styling for library system
Sketch of module system