fix incomplete links, improve calendars (#799, #800)

global (frontend views):
- fix incomplete links (missing "option=com_jem")
calendar related:
- fixed weekcal span in month rows, added <tr css classes
- calendar class robustness, allow caller to give link to day view
- allow styling of things like "today is sunday"
- fix hiding of events (there was an empty box left)
Merge branch 'development' of https://github.com/jemproject/JEM-Project into development