This commit splits the production, injection, and cumulative
*Report_() functions into three logically distinct parts, one for
outputting the report header (begin*Report_()), one for outputting a
single report record (output*ReportRecord_()), and one for ending
the report (end*Report_()). This simplifies the logic of the
*Record_() member functions since they no longer need to infer the
context which is already available in the caller and can perform a
more narrow task than before.
With this separation we're also able to remove the dashed lines
which would previously separate each report record, thereby creating
PRT file report sheets which have a more expected layout.
Moreover, as an aid to future maintenance, we also factor out common
code for the well and group cases in each *Record_() function.
Finally, fix a unit conversion problem in the report values for
cumulative gas quantities. The sheet header states that we should
be outputting values in 'MM' prefixed units, but we were only
scaling the gas values by a factor of 1000 instead of 1000*1000. In
other words, the injection and production gas values in the
cumulative sheet were off by a factor of 1000.
