task 3: Remove ".sh" from linux execution script 
https://github.com/arnehaber/xmind2latex/issues/issue/3
task 4: Add parameter to control until which level templates are used 
https://github.com/arnehaber/xmind2latex/issues/issue/4
task 5: Undefined entries (printed as comments) indented by level 
https://github.com/arnehaber/xmind2latex/issues/issue/5
adjusted docu for issues #2, #3, #4, and #5