Recursive Directory Searching for Multiple File Specs

Searches a directory for multiple file specs with optional recursivity

dir2 List directory.
DIR2('directory_name') lists the files in a directory. Pathnames and
wildcards may be used. For example, DIR *.m lists all program files
in the current directory.

DIR2('directory_name','-r') Lists the files in a directory, and it's
subdirectories.

DIR2('directory_name',filter1,filter2,...) Applies the filters FILTER1
and FILTER2, etc to the directory search. These filters are treated as
an OR. Thus a file must only match atleast one filter to be included.
Filters may be strings, or cell arrays of strings.

DIR2('directory_name','-r',filter1,filter2,...) The recursive flag and
the filters may be in any order.

D = DIR2('directory_name') output the results in an M-by-1
structure with the fields:
name -- Filename
date -- Modification date
bytes -- Number of bytes allocated to the file
isdir -- 1 if name is a directory and 0 if not
datenum -- Modification date as a MATLAB serial date number.
This value is locale-dependent.

EXAMPLES:
Example 1: Recursive directory listing of the current directory
d = dir2(pwd,'-r')
{d.name}'

Example 2: Using multiple filters
d = dir2(pwd,'*.mat','*.m')
{d.name}'

Example 3: Using multiple filters w/ a recursive search
d1 = dir2(pwd,'*.mat','*.m','-r')
d2 = dir2(pwd,'-r','*.mat','*.m')
% Notice order of the flags doesn't matter
isequal(d1,d2)

NEW: Now implemented also as MEX file. Unfortunately only windows is supported for the MEX file, but the .m version is fully function regardless of OS. The MEX version seems to provide a ~20x speedup over the .m implementation. Syntax is identical, and will mex itself (assuming you have a compiler)