StringConverterTest: Use the same strings as everyone

When you translate " yeah " you might get another result than
"yeah" since they are different strings. Dont do that.
Filter: Rename tear_up() to set_up()
Filter: Improve docstring
Filter: Fix __send_msg() to place delimiters as expected
License: Remove doubled blank before last sentence in various files
StringConverter: Convert value to string before use

This provides the assumption that __value is a string which is used
in the whole StringConverter class.
StringConverter: Use ValueError instead of AttributeError
StringConverterTest: Add test for failed int conversion
StringConstants: Add COMPLEX_TEST_STRING
LogMessageTest: Use COMPLEX_TEST_STRING for testing
TestHelper: Use # for test seperation

Test output is now separated by line of hashes (#) because equal signs
(=) are already used on failures.
LogMessage: Convert message to string