Support for using bam to run lua scripts

Adds support to run bam as a lua interpreter with a script file as argument. It also adds support for -- on the command line, which will parse all subsequent arguments as script arguments. These arguments are put in the ScriptArgs lua global as with the usual args (argname=val). Unnamed args will be put into the array part of the ScriptArgs lua global.

Example:

    AddJob("outfile", "lua infile", "bam -e example.lua -- -o outfile infile")