Gzipped input support - Githubissues

Description

As a user I want to use the mapper directly with gzip-compressed files.

[ ] Find a gzip library (zlib.h is multi-platform).
[ ] Write code to detect whether input file is gzipped.
[ ] Update code to read input file using zlib functions.
[ ] Embed the library in the software (no complicated installs!).
Acceptance criteria
[ ] The software distinguishes between compressed and plain files without extra parameters.
[ ] A plain input file and its compressed version produce the exact same result.
[ ] Installing/compiling the software does not require any additional step.
[ ] The software supports the same platforms/OS as before.
Test procedures
[ ] Unit tests with compressed versions of the test example files.