export or not the names from NCurses

[jmichel7]

Apparently, you stopped exporting most names from NCurses in the commit 3 months ago. I do not know why, since if one wants to write an NCurses program it is convenient to have the names of the NCurses functions available. But the point of this issue is that you have not been consistent, the constants in the file ncurses_attributes.jl are still exported.

[ronisbr]

I select this path to avoid poluting the namespace. Hence, all the functions must be called as NCurses.<function name>. This approach is better IMHO.