Add gffread (viash-hub#29)

* Uploading local copy

* Restructured directories and changed test data source and script

* Create var/ssoftware_versions.txt

* moved file and added quotes to all filenames

* Small formatting changes, add command tag to config file

* unset flags in script.sh and fixed argument types in config

* Refined tests

* Adjust comments

* Add changelog description, add config keyword and reorder lines

* Resolving the suggestions for PR 29

* Delete unused files

* Make output file argument required

CHANGELOG.md

@@ -29,6 +29,8 @@
 
 * `star/star_align_reads`: Align reads to a reference genome (PR #22).
 
+* `gffread`: Validate, filter, convert and perform other operations on GFF files (PR #29). 
+
 ## MAJOR CHANGES
 
 ## MINOR CHANGES