[16Edit] preoperly open files >4GB

[roytam1]

it will still need using 64bit to open >4GB files because it use memory mapping to open file.

for now it opens in 64bit build, but only displaying (filesize % 4GB) bytes, as a result many places needed to be changed for 64bit.

[roytam1]

File.cpp needs to be modified for 64bit file size support first.