refactoring in preparation for asymmetric error bars
refactoring to prepare asymmetric error bars
added support for asymmetric error bars in \addplot table {<inline>}
added test cases
added asymmetric error bars for \addplot table {\loadedtbl}
added tests
implemented asymmetric error bars for \addplot coordinates {...}
added tests
added asymmetric error bars for \addplot3 coordinates
added tests
improved tests
updated changelog
documented asymmetric error bars