Fix an issue that prevented harlock to correctly make build fails on …

…runtime

and evaluation errors being raised, using non-zero error codes correctly. Fix
minor issues with the builds and with repo management.

changed: moved the hex parser to /pkg.

fixed: builtin descriptions; elf.write_section was accepting any obje…

…ct as the array parameter.

added: new release info and feature descriptions for v0.4.0.

fixed: printing a nil value caused a runtime panic.

fixed: typos in the permission numbers caused problems in *nix builds…

…; substituted deprecated methods and temp names.

changed: added examples for the hex type in the README.

changed: fixed makefile phony directives.

changed: added errors as values and try expression support + tests.