Fix cpplint warnings

Optional value needs to test explicitly the comparison operators => use // NOLINT
WriteText/ReadText use printf %lld %llu, so we have to use a cross plateform type <unsigned> long long int => use // NOLINT
Merge branch 'master' of git.assembla.com:OpenSurgSim
Merge branch 'fix/cpplintWarnings' into 'master'

Fix cpplint warnings

+1: haizhouW, Gughan Sathyaseelan, Ryan Beasley

Merged-on: https://www.assembla.com/code/OpenSurgSim/git/merge_requests/1090783