Build 3.0.0.162 of xlsgen includes a number of fixes related to reading the internal records of XLS and XLSX charts, and sometimes also for writing back to files.

In details :
- proper reading of datapoint-level line markers in XLS charts
- bugfix : why is the first data label element not appearing sometimes? That was due to an incorrect BIFF read.
- read custom (x,y) data label position for XLS charts
- XLS : read number format for data labels
- better reading of indidivual data labels formatting
- better reading of automatic line markers
- support for the BIFFEXT record wrapper in the chart (better data label reading)
- read and write bubble chart properties from XLS and XLSX files.
- better smooth-line reading and exposure from XLS and XLSX charts