Fixed build error on VS 2013

unsigned __int64 ~= unsigned long long.  VS2013 will error.

link gomp only if openmp found

fix mingw x86_64 build

do not install flann matlab lib

Extend CenterChooser initialization

Set DataSize (cols_) when loading an index

Fixes in accum_dist methods

Spelling corrections

Correct spelling

Correct spelling

Add a new method for initializing KMeans centers that leads to better clusters and thus better retrieval when final centers have to be existing keypoints instead of clusters barycenters.

Fix CMakeLists.txt for MSVC

if(<string> MATCHES ...) cause incorrect definition for MSVC. Reference: http://stackoverflow.com/questions/21995777/cygwins-cmake-does-not-match-for-cmake-system-name

Update nn_index.h

-1.

dimensions instead of the number of points.

a bugfix

flann_get_distance_order functions.

it's all working again. Mysterious.

while I sort that out. This also adds the max_k option to radius_search
as discussed in #170.

assist in debugging set_distance_type in the Ruby API.

testing manual code.

in the manual. Added a way of initializing FFI::Structs from a hash,
converted defaults into a hash. Defaults now seem to work.

set_distance_type! is marked as pending.