Opencv detection, Makefile cleanup

[linuxkidd]

• Updated all cvFunction to cv::function, etc.. format to be compatible with OpenCV4.
• Updated Makefile to work for either OpenCV or OpenCV4 libraries.
• Updated Makefile to exit when dependencies were not found by pkg-config.
• Updated Makefile to exit when the platform is not known.
• Removed deprecated systemd service terms.

NOTE: I had quite a bit of issue getting the Display() function to compile, but finally got something workable -- although, I've not tested the Display capability. I would love for someone to test the Display code prior to merge. Otherwise, the rest of the code compiles fine on both Raspberry Pi OS based on Debian Buster with OpenCV 3.2.0, as well as Debian Bullseye with OpenCV 4.5.1.

Resolves #508
Resolves #509

[ckuethe]

Reviewing now, just looking to see if I have an old-enough debian machine or if I have to spin up a VM or something.

[ckuethe]

Just a few remarks on the Makefile, the c++ changes seem to work for me on x86_64.

[ckuethe]

Oh, one more change to Makefile: suggest that the user needs to install libusb-1.0-0-dev or something similar. At least on my machines libusb-dev would install libusb-0.12-dev.

[linuxkidd]

@ckuethe So, overall, seems like we don't need the DEFS += -DOPENCV_C_HEADERS for any platform.. which also likely means we don't need the conditional include at the top of capture.cpp which looks for that define... right?

#ifdef OPENCV_C_HEADERS
#include <opencv2/core/types_c.h>
#include <opencv2/highgui/highgui_c.h>
#include <opencv2/imgproc/imgproc_c.h>
#include <opencv2/imgcodecs/legacy/constants_c.h>
#endif

-- this can all be removed? ( I'm pretty sure the answer is yes, just confirming )

[ckuethe]

Indeed, it looks like you can get rid of that #ifdef everywhere.

[ckuethe]

Thanks for helping make Allsky better. :)

[linuxkidd]

Likewise!