color: add win32 support for non-black background
This complicates the code a bit, since attributes need to be masked together
correctly before they are applied. Perhaps the code should be redesigned at
some point, but this works well for now.
% test default params, display nothing because of delay
% test with delay=0, refresh=0
loop [ ] 0/3
loop [=====================> ] 1/3
loop [============================================> ] 2/3
% test refresh is taken in account
% test format options 1
0/2 loop lo
1/2 loop lo
% test format options 2
0/2 p.0 [ ]
1/2 p.1 [=================================> ]
% test format options and indeterminate progress
0 loop.0 [ <=> ]
1 loop.1 [ <=> ]
% make sure things don't fall over if count > total
loop [ ] 0/4
loop [================> ] 1/4
loop [=================================> ] 2/4
loop [==================================================> ] 3/4
loop [===================================================================>] 4/4
loop [ <=> ] 5/4
% test immediate progress completion