Removed unnecessary .calls and .applys from Axis.initializeScale.
Removed the separate findMax function definition from each series.

All series now use the base Series findMax function.
Added Chart.seriesIndexByType for supporting positioning of multiple row or column series in one chart.
Minor renaming: groupedbarThickness => groupedBarThickness
Fixed error declaring private variable.
Tests for findMax on each series
Updated comment for Chart.seriesIndexByType and added an example.
Merge pull request #144 from niksoper/tidyup

Tidying / refactoring before removal of sub-series.