mpwt 0.5.5

[ArnaudBelcour]

Add:

• support for .fsa extension (issue #47).
• a license (issue #45).
• a --version argument to mpwt command-line (issue #44).
• pseudogene linked to mRNA in topf (issue #30).

Fix:

• issue with encoding in mpwt_wrapper.
• issue when --md could be used without -o argument (issue #46).

Thanks to @cfrioux for her work on this release.