Make the argument file (option file) more readable

[eldipa]

Describe the feature you'd like

The =

When using @boptions, the file boptions needs to have 1 argument per line. When an argument receives an argument (confusing wording here), you need to use = or use multiple lines:

-l=python

or

-l
python

The idea is to be able to use a space as a separator instead of =

-l python

This does not solve all the problems however: when multiple arguments are required, with and without = will yield an invalid file:

--skip=foo bar baz

This is because foo bar baz will be seen as a single argument and not three and obviously such file does not exit.

And we cannot do much about it, the following are currently valid and depends on this "single argument per line" premise

-x-shebang=%e %p %a

Comment lines with #

We can support empty lines and lines that starts with # and treat them as comment.