[Enhancement] Add Support for Common 2nd Suffixes (Fix #84) (#6)

[kevinmatthes]

When working on large projects, one often utilises several automation techniques in order to abbreviate redundant tasks, such as the build instruction specification by hand over and over again for every single build process. Another common example is testing where not only unit and integration but also mutation tests can be specified.

In order to set up such an automation, one needs to apply the conventions of the respective build system. The autotools suite, for instance, expects some input files to have the *.in suffix and will generate processed source files with the *.out suffix. On the other hand, some build steps may be destructive such that the system itself needs to take care to prevent a loss of progress. mutmut, a Python library for mutation testing, for example, creates backups of the respective source files which have the *.bak suffix.

All those systems have in common that one might want to take a look into the newly generated files for getting an idea which changes the respective system has applied. But then, Zee currently falls back to the plain text mode without any highlighting since the suffix could not be matched if not explicitly specified in the configuration.

This Pull Request challenges this disadvantage by the introduction of a matching against the common second suffixes named above by default against each file. Furthermore, already configured second suffixes were removed from the configuration since they are implicit by this change, now.

[kevinmatthes]

I admit that this is not the most performant solution but as a first suggestion, it replaces the previous obligation to add any suffix combination by hand. I am working on a more efficient solution which I am going to submit when I finished. Until then, this workaround seems to be not the worst option, at least in my opinion, such that I consider it ready for merging, anyway.