FeatureVector/Cleanup: Fix up comments of destructive operations
FeatureVector: Switch to using single-precision floats internally to save memory
Text/math: Redo formatting of long/double integrating comma-output, with_commas -> pretty_long/pretty_double, add math.is_negative for handling -0.0 correctly
metering/os/time: Clean up resource output, add format_bytes, format_minutes_seconds_short, metering.time_action
MLogit: Output timing stats for various operations
Reranker: Fix up output of feature-vector usage stats