Fixed directsound PaDeviceInfo default latency and PaStreamInfo latency fields. Fixed...

Fixed directsound PaDeviceInfo default latency and PaStreamInfo latency fields. Fixed host buffer size calculations based on suggestedLatency parameters. Switched to using 48kHz as default sample rate when other info isn't available. Fixed edge case in TimeSlice() where a full duplex stream could read data even though either input or output reported zero bytes available. Renamed some variables for clarity. Fixes ticket #160 (PaStreamInfo latency). Addresses #122 (although we're still using old default latency values from V18 codebase). Addresses #99 (correct interpretation of suggestedLatency down to zero).