Clarify manual on different/inconsistent ordering of variables used in description of decision rules

The previous description used the same variables to denote both declaration and DR order, thus confusing users.
Merge pull request #484 from JohannesPfeifer/manual_DR

Clarify manual on different/inconsistent ordering of variables used in d...
reporting: add new series option tableSubSectionHeader
reporting: series: fix spacing of table cell separators and eol's
reporting: series: tableRowColor add missing check
reporting: table: remove unused variable
reporting: fix hline for table
reporting: annualAverages option for addTable
reporting: make tableSubSectionHeader prettier when vlineAfterEndOfPeriod is true