More appdata files!

I've sent as many as I could upstream, either via their trackers, pull
requests or via mail to the contact author.

There are a few issues, such as missing screenshots:

[asinha@ankur-laptop  appdata-files]$ for i in *; do echo "** $i **";
appdata-validate "$i"; done
** freediams.appdata.xml **
freediams.appdata.xml 1 problems detected:
• style invalid         : <li> is too short
** freemedforms.appdata.xml **
freemedforms.appdata.xml validated OK.
** kapow.appdata.xml **
kapow.appdata.xml 1 problems detected:
• style invalid         : Not enough <p> tags for a good description
** labyrinth.appdata.xml **
labyrinth.appdata.xml 1 problems detected:
• attribute invalid     : <screenshot> width was too small
** lifeograph.appdata.xml **
lifeograph.appdata.xml 2 problems detected:
• style invalid         : <li> is too short
• style invalid         : <li> is too long
** lingot.appdata.xml **
lingot.appdata.xml 3 problems detected:
• attribute invalid     : <screenshot> height was too small
• attribute invalid     : <screenshot> width was too small
• style invalid         : <li> cannot end in '.'
** memaker.appdata.xml **
memaker.appdata.xml 1 problems detected:
• style invalid         : Not enough <screenshot> tags
** Panini.appdata.xml **
Panini.appdata.xml 1 problems detected:
• style invalid         : Not enough <screenshot> tags
** subtitleeditor.appdata.xml **
subtitleeditor.appdata.xml 1 problems detected:
• style invalid         : Not enough <p> tags for a good description
** tagtool.appdata.xml **
tagtool.appdata.xml 1 problems detected:
• style invalid         : Not enough <screenshot> tags
** xmedcon.appdata.xml **
xmedcon.appdata.xml validated OK.
[asinha@ankur-laptop  appdata-files]$
Merge pull request #9 from sanjayankur31/more-appdata-files

More appdata files!