Fix absolute paths in scripts

[knarfS]

This removes some of the wrong paths pointing to the build location of the AppImage by using a different shebang and some environment variables.

Fixes #12, Fixes #25 and Fixes #32

I left out some of the scripts, like:

• AppDir/usr/conda/shell/condabin/conda-hook.ps1: No need for Powershell
• AppDir/usr/conda/conda-meta/*.json: dunno...
• AppDir/usr/conda/lib/*/*.sh: Some config scripts, not needed I suppose?
• AppDir/usr/conda/lib/pkgconfig/*.pc: pkg-config files, not needed and no idea how to fix them.
• AppDir/usr/conda/lib/python3.8/*/*.py: dunno...

I only have a base install of conda with no extra packages, so probably not all possible files are covered. Also some of the regex could be a little bit more sophisticated...

[knarfS]

I've added an additional replacement for 32bit conda installations.