Fix some issues in the Bash engine

[beatussum]

This pull request refers to this issue I reported some days ago.

It's not perfect but it should do the job in most of the cases.

I tried to respect your coding style. I hope I haven't made mistake and I'm waiting for review.

All tests passed.

[SimonKagstrom]

Thanks!

You had a great example in the issue, is it possible to add that to a small test case?

Bash parsing is fairly nasty. The python support is much more slim, and easier to follow, but bash requires quite a lot of special cases. I had hopes of writing a proper parser, but with these changes (and some other), it's probably good enough as it is!

And as for the coding style, I've started to change it in some files, so right now everything is in flux and your changes look good to me :-)

[beatussum]

I've dropped the commit which was supposed to fix coverage of multiline arrays. Indeed, it seems to be quiet difficult as trap <arg> DEBUG does not have the same behavior with the different syntaxes used to initialize an array:

trap 'echo ${LINENO}' DEBUG

declare -a array=( # <- this line
    a
    b
    c
)

declare array=(
    a
    b
    c
) # <- this line

declare array=(
    a
    b
    c
) # <- this line

[SimonKagstrom]

Merged, thanks a lot!