Implemented the missing ocSub operator
Implemented the missing ocSub operator

Added support of ocSub. Commented that the operand order is actually
reversed in Childen array of FormulaTreeNode.

Change-Id: I7cf57e4c440d4f7b4e70530dd3129c199ace1f7c

JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core