Bug fixing and update tests

Fixed erroneous overwrite warnings
Updated testfiles to current Freeplane version

Bug fixing

More unit tests
Updated documentation

New to-do list behavior more in line with real-world examples

Refactoring: Several code simplifications

Phrasing in documentation

New patch version

Conversion of icons "executable" and "video"

Always use UTF-8 encoding for output, resolves #14
Use raw strings for REs to fix deprecation warning

Prevent erroneous overwrites of target files, closes #13

Insert diagnostic comment with timestamp
Do not overwrite, if modification time of file is newer than timestamp; exit with message.
Add command line options
Add documentation

Update release to 0.8

Version 0.7

Version 0.6