Update: implement and use more global values, simplify http response return values...

Update: implement and use more global values, simplify http response return values, implement content-range, other changes/fixes

The time functions have been moved into the global default class.
The http language class has been moved into the global default class.

The return values for HTTP response functions have been set to their specific type, instead of always FALSE.
This makes it easier to handle the return value without caring about errors.
Any unsupported functionality continues to return FALSE until such time I read the appropriate part of the standards and implement the functionality.

Content-Range response is now implemented.

I noticed that I have been inconsistently using $ps_ and $s_ for private static class variables.
I removed $ps_ that in favor of $s_ only because it was the simpler change.
I may end up coming back later and changing all private static to $ps_ (or not..).

While making the time values global, I noticed that PHP does not always guarantee microseconds to be populated.
Special handling is necessary and so I created more global static functions to handle this complicated situation.

I've observed and fixed some simple mistakes, bugs, typos, etc...