adds pie charts and combination charts
Created originally on Bitbucket by aceMueller
built on 424; includes test cases; mercurial bundle attached; adds both PieChart and combination chart (i.e., support for alternate axis where different series' Y values are on right side from those on the left side; combined into one build because some of the code falls into the same functions, so this was the most practical way to send both changes without waiting until the repository is updated for one before sending the other; also includes 2 fixes for a min-max function - one failing when all values for a series are 0, and the other failing when the value is such a small or large value that the basic float function returns scientific notation, the string of which fouled up the rest of the code (substituted a format operation with sufficient digits specified).
Attachments: addPieChartAndComboChart