* Fixed type passing to opencv to use basic instead of aggregate.

* Change tabs to spaces.

background crops.

numpy's import_array() in a more robust way.

void*.  But the previous code didn't so it wouldn't compile.  Fixed that
problem.

* Exposed jitter_image in Python and added an example

* Return Numpy array directly

* Require numpy during setup

* Added install of Numpy before builds

* Changed pip install for user only due to security issues.

* Removed malloc

* Made presence of Numpy during compile optional.

* Conflict

* Refactored get_face_chip/get_face_chips to use Numpy as well.

look at issue:
https://github.com/davisking/dlib/issues/674

the old win32 functions.  I did this to work around how windows unloads dlls.  In particular, during dll unload
windows will kill all threads, THEN it will destruct global objects.  So this leads to problems
where a global obejct that owns threads tries to tell them to shutdown and everything goes wrong.
The specific problem this code change fixes is when signaler::broadcast() is called
on a signaler that was being waited on by one of these abruptly killed threads.  In that case, the old
code would deadlock inside signaler::broadcast().  This new code doesn't seem to have that problem,
thereby mitigating the windows dll unload behavior in some situations.

dlib 19.7 the padding code was changed and accidentally doubled the size of the
applied padding when in the older (and still default) landmark_relative padding
mode.  It's not a huge deal either way, but this change reverts back to the
intended behavior.

output correlation rather than squared correlation.

* disjoint_subsets: make clear and sizde functions noexcept

* disjoint_subsets: add get_number_of_sets function, documentations and tests

* disjoint_subsets: add get_size_of_set function, documentation and tests

* Split disjoint_subsets in a hierarchy.

Modify disjoint_subsets to make it a valid base class.
Add new class disjoint_subsets_sized, with information about number of
subsets, and size of each subset.
Add necessary unit test for the new class.

* Replace tabs by spaces.

* Remove virtuals from disjoint_subsets, and modify
disjoint_subsets_sized.

Now disjoint_subsets_sized is implemented in terms of disjoint_subsets,
instead of inherit from it.