Czech translation update

Hi,
this is the czech translation of both frontend and backend of JEvents 1.5 Stable [1441].

[attachment=0:91j773uq]<!-- ia0 -->cs-CZ.com_jevents_1.5stable_1441.zip<!-- ia0 -->[/attachment:91j773uq]

Unfortunately I have not noticed that there is already czech translation made by Jan. So maybe this is a duplicate work. Sorry for that. Anyway the bz2 seems to be corrupted on my PC.

I have also some other comments. Not sure whether they are applicable.
* translation tags collide with the joomla-wide tags, for example the HELP. would be great to have them all prefixed with JEV_ or something else
* untranslatable strings I have found so far:
[i:91j773uq]Display Num[/i:91j773uq]
[i:91j773uq]Select Ical (from raw icals)[/i:91j773uq]

of course comments are welcome

thanks for this great component!
Pavel

{I have updated this post, 'cause I uploaded the version without help first. Now it should be complete}