easyplot:  - make nicknames optional  - function for loading journal files (json)  - add journal attribute  - dont allow for both filenames and journal filename (raises ValueError)  - make file default to None  - merge filenames to a new name if list of list of files is given  - populate self.files from journal
easyplot:
 - make nicknames optional
 - function for loading journal files (json)
 - add journal attribute
 - dont allow for both filenames and journal filename (raises ValueError)
 - make file default to None
 - merge filenames to a new name if list of list of files is given
 - populate self.files from journal

 Next: populate mass

jepegit/cellpy,jepegit/cellpy