Enable code coverage reports, implement new unit tests, minor improvements in code and fixes in test data

[gkostkowski]

Scope of the changes:

• Implemented a script for manual coverage reports generation
• Implemented a script for calculating coverage score
• Added unit tests for 2 functions and 5 templates
• made specification of f:normaliseURI function more precise and added a safeguard for unsupported values
• Introduced a new test file with a global variable overwritten for the included test purposes
• Removed trailing spaces in test data (as this was causing some code to fail)
• Fixed a typo
• Added XSpec script with a bug fix to be used manually