Add regular expression parameter to mastermap command

[risserlin]

Add the ability to select a subset of folders in the given directory to create a mastermap. For example, filter_by = "heart", only directories in the given directory where the names contains the word heart will be included in the mastermap.

[mikekucera]

I think its more intuitive to use the glob syntax that you typically use on the command line. For example if you want folders that start with gprofiler you would put pattern="gprofiler*". The equivalent regular expression would be ^gprofiler[^/]*$.