NaN is encountered.

in some cases.

Added Travis badge  ![badge](https://travis-ci.org/davisking/dlib.svg?branch=master)

If temp is nonzero but a subnormal then temp2 matrix may contain infinities which may cause temp assignment in line 225 to be a NaN (as a difference of two positive infinities).

user confusion.

file a little clearer on this issue.

--HG--
rename : dlib/matlab/mex_example_class.cpp => dlib/matlab/example_mex_class.cpp

the documentation.  I also updated a few places throughout the docs to say that
you need a C++11 compiler.

organized in the HTML documentation.