Eliminate unnecessary version checks
Fix to number format masking for scientific notation
Minor performance tweaks to calculation engine
Performance tweaks
Performance tweaks
Merge branch 'develop_1.7.9' of https://github.com/PHPOffice/PHPExcel into develop_1.7.9
Performance improvements
Minor performance tweaks
Merge branch 'develop_1.7.9' into develop_2.0.0