color: set initial default value for 'colormode' to None This should not introduce any behavior changes when using the color extension. In practive, the colormode will be setup at early at run time to the proper value (from config and environment). We do this change as this gets us closer of a state were we can have all the mechanisms associated to color in core with the feature disabled by default.

color: minor reversal of two conditional clause for clarity Another minor cleanup while reading the code. The two branches of the conditional have similar complexity so we go for the order that give us the simplest condition (we drop the negation).

color: merge two identical 'for' loops The previous changeset made it clear that we are iterating twice on the same items. We gather the two loops into a single one.

color: minor simplification of some terminfo setup code No logic change is introduced. The previous code were using a 'dict.update' with a complex generator. That was a bit confusing to read and not so compact. Instead we now use an explicit loop and conditional for the sake of clarity. This also allow for more simplification coming in the next changeset.

color: make a test for curse availability explicite We won't use terminfo when curse failed to load. Before this change, we were doing an indirect test, relying on the fact some variable ('_terminfo_params') would be empty if curses failed to load. We update the code to be more explicit and directly checks if we managed to load the curse module.

color: move 'win32' declaration to the core module This is another part of moving color implementation into core. before we can move the advance logic, we need to move the basic definition and building bricks. This is one more step on that road.