Avoid raw reinterpret_casts in the FBX parser

As reinterpret_cast can break strict aliasing rules, causing runtime failure
on Android, replace such usage in FBXParser with memcpy.  Also provide a
utility routine for both performing the copy and asserting the validity of
the buffer length relative to the copied region.
CMake: changed cached bools into "option"
fix some compile  warnings:
- passing NULL to non-pointer
- unused vars
- unused function
- order of init
- parentheses
fix warning:

equality comparison with extraneous parentheses
fix SimpleOpenGL linking (missing libm)
Merge pull request #332 from abma/master

some minor fixes
fix unittests on linux / enable on travis-ci
fix compiler warnings:
- defined but not used
- deprecated conversion from string constant to ‘char*’
Merge pull request #333 from abma/master

fix unittests on linux / enable on travis-ci
Merge pull request #334 from jdduke/fbx_binary_fix

Avoid raw reinterpret_casts in the FBX parser
fix most warnings with -pendantic
Merge pull request #335 from abma/master

fix most warnings with -pedantic
Gracefully handle NaN/inf values in fast_atoreal_move

There are legitimate cases where inf/nan values are embeddded in a mesh.
Such values should not cause loading to fail, and indeed, previous versions of
Assimp supported their existence. Update the new fast_atoreal_move method
to gracefully parse such values, allowing case-insensitive checks for "NAN",
"INF" and "INFINITY" as per the atof guidelines found at
http://en.cppreference.com/w/cpp/string/byte/atof.

Note that the inf/nan text parsing is fairly loose, but is fast for the general
case and should handle most legitimate inf/nan values.
Merge pull request #338 from jdduke/fast_atof_fix_final

Gracefully handle NaN/inf values in fast_atoreal_move
Collada Export: escape user-defined strings in XML output.
Merge pull request #344 from assimp/collada_export_escape

Collada Export: escape user-defined strings in XML output.
Collada : Add missing parsing <image> into <effect><profile> markup
Merge pull request #347 from vloppin/master

Collada : Add missing parsing <image> into <effect><profile> markup
start assxml exporter basics
convert assxml exporter