STYLE:Empty commit just add information about rev 1.15: the reason is that...

STYLE:Empty commit just add information about rev 1.15: the reason is that long is 64-bit on gcc on Linux because it uses the LP64 data model whereas long is 32-bit on VS 64-bit because it uses the LLP64 model (ref: http://en.wikipedia.org/wiki/64-bit#64-bit_data_models )