New release 3.30

• the data directory can be defined with the HIGHLIGHT_DATADIR environment variable
• fixed RTF output of UTF-8 input; needs input encoding set to utf-8
• fixed XML comment recognition
• data search directories were appended to the result of --list-scripts
• revised older syntax definitions
• updated base URLs of bash_ref_linuxmanpages and cpp_ref_qtproject plug-ins
• GUI: added system copy and paste shortcuts for clipboard functions