Revert last commit "All exceptions raised ..."

This reverts commit b053cdc0719ca9a9d2c532fb26b396f5717dd582.
Add target directory to .gitignore

Add the target directory to .gitignore according to convention.
Add error location for all compilation errors

All exceptions raised during compilation due to compilation errors
now contain positional information about the error in the source code.

This was missing in particular by various causes of
UnknownIdentifierException as well as UnknownTypeException. The
changes are reflected by the accordingly modified ("negativ") test
cases, namely neg_Function* and VariableAccess*.