use lower-case input by default under Linux
Added missing constructor initializer.

-- Detected by CppCheck 1.6.5
Added missing constructor initializer(s)

-- Detected by CppCheck 1.6.5
Merge branch 'master' of https://github.com/bgossage/bullet3 into uninitialized_members
Merge branch 'master' of https://github.com/bulletphysics/bullet3 into uninitialized_members
New from the backup branch
Added missing constructor initializations.

These were detected by CppCheck version 1.6.5