Rework README file

[rockstorm101]

Modernize the README file by adding some new sections and deleting out-of-date information. As always, any feedback/criticism is welcome :)

[DivingDuck]

I like this modernized version very much.

[neofelis2X]

The updated readme is beautiful! A few details that I noticed tho:

Dependencies, line 128:

• pyglet has to be below 2.0 (1.5.27) due to legacy OpenGL support
• numpy (for 3D view) - Isn't numpy also used by the STL plater to import stls? Maybe (for Pronterface) should be added instead.

From source, macos, line 212:

• It is generally not recommended to install python via brew unless one really knows what they are doing. Python via brew can get a bit involved regarding PATH and versions. Especially for beginners it is saver to use the official installers. https://www.python.org/downloads/macos/

[rockstorm101]

Dependencies

You are right. I thought about this and forgot. My concern here is: is it really worth keeping a list of dependencies in the README or should we just point to the requirements.txt file? The two lists will likely fall out of sync (has already happened as you rightly pointed out) and it is more tedious to maintain. It'd be great to hear what people think about this.

It is generally not recommended to install python via brew unless one really knows what they are doing. Python via brew can get a bit involved regarding PATH and versions. Especially for beginners it is saver to use the official installers.

Such a claim goes beyond my knowledge so I'm happy with it if you think that's the best for the average novice macOS user. Thank you for pointing that out, this will probably save some headaches to future users. I believe this recommendation goes back to when Python 3 wasn't readily available. So it makes sense that it is no longer relevant any more. I will attempt to address this now but please do not hesitate to send a PR in with updated instructions if you see room for improvement.

[neofelis2X]

Yes, absolutely, having two detailed lists of dependencies would be redundant.
Nice, I have nothing to add to this solution :)