Add command line options for e.g processing files and others

[xoofx]

kalk is a command line app but doesn't have options to use it outside of its interactive mode

• e.g --file=input.kalk to process an input file
• or to print its version --version
• or to predefine some variables passed from the command line e.g `--set="x=1"
• or to evaluate an expression from the command line --eval="x = 1; x + 2"
• or simply --help to print all these options

We need to define what we can allow to do here.