Update of Czech translation
to make better sense in the menu
Merge remote-tracking branch 'upstream/master'
added function to import/export data, but it does not work perfectly at
the moment...
update "Add Homework" page
add permission to read external storage
moved import/export to own method
do not hardcode directory in /data/data
auto-formatted the whole code with eclipse
combine cutted strings to one, i. e. "hwid"+"_size" to "hwid_size"
Merge pull request #4 from AltNico/develop

Update