how about public methods to flush date/location

[knormoyle]

to be used when you send a warm or cold reset to the gps chip, and don't want to be using any old state in TinyGPS++ anymore..i.e. want to wait for new state from gps chip after it's reset

i.e. a need to flush date and location state:

TinyGPS++.h

in TinyGPSLocation

//***************
// HACK: make public method and cover fixQuality and fixMode also
void flush() { updated = false; valid = false; }
void fixQualityFlush() { updated = false; fixQuality = Invalid; }
void fixModeFlush() { updated = false; fixMode = N; }
//***************

in TinyGPSDate

//*************
// HACK: make public method
void flush() { updated = false; valid = false; date = 0; }
//*************