Celestia: Build instructions

Clear and easy build instructions/method would attract more developers to contribute to Celestia.
Most successful and growing projects are usually those that are not only user friendly but also developer friendly.

yes I agree. Currently you can resort to the INSTALLATION file in the root directory for building.

We will need to rewrite that file in markdown to make it more friendly

Please refer to https://github.com/CelestiaProject/Celestia/blob/master/INSTALL, both MSVC and GCC (Mingw) are supported.

IMHO build method described here https://github.com/CelestiaProject/Celestia/blob/master/INSTALL is so complex and time consuming that some developers wouldn't even think to try to build the Celestia by themselves leave aside contributing. This method is so discouraging.
IMHO all ThirdParty libs should be integrated in Celestia repository which could be downloaded using git clone --recursive https://github.com/CelestiaProject/Celestia.git or directly using git clone https://github.com/CelestiaProject/Celestia.git. This way the developer would only need to build and run the project that's it. At least core project should be easy to build and run. The optional packages can be allowed to be configured through vcpkg.

I would like to see how you integrate GNU gettext, without official support for MSVC and CMake, GLEW (autogenerated, so it requires 2 stage build), lua and libpng. I also would like to see how you recompile Qt every time you change the main CMakeList.txt or pass another option to CMake.

Let's gradually make the build instructions better so we can get even more contributors!
I've started softly with #573 ...

@eyvallah : Would you like me to rewrite it in Markdown?

@eyvallah : Would you like me to rewrite it in Markdown?

That would be great, go ahead

@eyvallah : Here you go -> #579

Could probably use some linting and extra line breaks, but it's a start :-)