Bring Recast/Detour integration into working order.

[Maxwell175]

Issue description

This PR will massively cleanup the Recast/Detour integration and bring it into working order as of current master.

Solution description

This PR will fix the merge issues from moving up to latest master, overhaul the code to work reliably, bring the code into conformance with Panda3D standards, improve commenting.

Checklist

I have done my best to ensure that…

• …I have familiarized myself with the CONTRIBUTING.md file
• …this change follows the coding style and design patterns of the codebase
• …I own the intellectual property rights to this code
• …the intent of this change is clearly explained
• …existing uses of the Panda3D API are not broken
• …the changed code is adequately covered by the test suite, where possible.

[codecov]

Codecov Report

Merging #1268 (b590522) into gsoc/2020 (560e57f) will increase coverage by 12.03%.
The diff coverage is 30.76%.

@@              Coverage Diff               @@
##           gsoc/2020    #1268       +/-   ##
==============================================
+ Coverage       4.09%   16.12%   +12.03%     
==============================================
  Files           3746     3746               
  Lines         362945   363013       +68     
==============================================
+ Hits           14854    58529    +43675     
+ Misses        348091   304484    -43607     

Impacted Files	Coverage Δ
panda/src/collide/collisionSolid.cxx	23.37% <0.00%> (+22.14%)	⬆️
panda/src/collide/collisionSolid.h	50.00% <ø> (ø)
panda/src/device/inputDevice.h	50.00% <ø> (+12.50%)	⬆️
panda/src/linmath/lvecBase3_src.h	81.81% <0.00%> (+51.81%)	⬆️
panda/src/linmath/lvector3_src.h	75.00% <0.00%> (-25.00%)	⬇️
dtool/src/dtoolbase/pvector.h	100.00% <100.00%> (+91.66%)	⬆️
panda/src/display/nativeWindowHandle.h	56.09% <0.00%> (-7.80%)	⬇️
direct/src/wxwidgets/ViewPort.py	0.00% <0.00%> (ø)
panda/src/device/linuxJoystickDevice.h	100.00% <0.00%> (ø)
panda/src/display/nativeWindowHandle.I	0.00% <0.00%> (ø)
... and 1239 more

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[Maxwell175]

Current personal TODO list:

• Implement generating navmesh from bullet shapes.
• Figure out and implement use of nav mesh tiles for quickly adding dynamic elements to a nevmesh.

[janEntikan]

Getting this merged would be pretty rad.

[Maxwell175]

Added Nav Mesh Obstacles (Currently only cylinder, but other types like boxes are possible). This allows to have a large number of moving obstacles on the same navmesh.

TODO:

• Add the other 2 obstacle types
• Fix writing BAM files

[Moguri]

Where are we at with this? I think adding additional obstacle types could always be added later if need be. However, fixing BAM writing and the broken build config would need to be done prior to a merge. Anything else?

[Moguri]

Any updates? Do you think you'll be able to get to the remaining todo items in the next few months?

[Maxwell175]

Rebased on to master. Work will continue in #1606.