Allow spaces before the ascii STL header keyword

The text "solid" is the general STL header indicator that the file is in fact
an ascii STL archive.  Allows spaces to precede the "solid" keyword, providing
compatibility with exporters that insert such (non-compliant )spaces.
Merge pull request #106 from jdduke/stl_ascii_check

Allow spaces before the ascii STL header keyword
ColladaExporter: fix assertion in ::isalnum() when a special character > 0x7f is present in material names.
Merge branch 'master' of github.com:assimp/assimp
remove duplicate vectors when export obj format
fixed bad merge
whitespace fix
obj: Fix tabs causing vertices to be skipped

If an obj vertex definition 'v' is followed by a tab instead of a space,
the vertex definition is skipped.
obj: Add support for relative vertex indexing

obj files allow faces to specify indices relatively by using negative
integers. See vertex refering in http://www.martinreddy.net/gfx/3d/OBJ.spec
Merge pull request #138 from calvindhsu/master

OBJ: Add relative indexing support
using a custom compare function instead of a global aiVector3t less than operator
Merge pull request #136 from marshallExocortex/obj_exporter__unique_vector_export

remove duplicate vertices, normals and uvs when exporting obj format
PlyExporter: fix export format for compatibility with Blender and MeshLab (and the PLY spec). Fixes #122
Merge branch 'master' of github.com:assimp/assimp
Blender: iterative loading code for the linked list of scene objects, fixes #28 but is preliminary as it touches code that is normally machine-generated.
ObjExporter: request smooth normals.
Merge branch 'master' of github.com:assimp/assimp
update genblenddna.py script to include workaround for reading blender Base list.
Blender: new DNA loading code generated by genblenddna.py script, now machine-generates the previously hand-written fix.
Merge branch 'master' of github.com:assimp/assimp into blender-stackoverflow