Convert all time-based stats to be microsecond-based, improving accuracy of very fast events. Add bitrate average/peak.

app/app.pro

@@ -202,6 +202,7 @@ SOURCES += \
     streaming/audio/renderers/sdlaud.cpp \
     gui/computermodel.cpp \
     gui/appmodel.cpp \
+    streaming/bandwidth.cpp \
     streaming/streamutils.cpp \
     backend/autoupdatechecker.cpp \
     path.cpp \
@@ -239,6 +240,7 @@ HEADERS += \
     gui/computermodel.h \
     gui/appmodel.h \
     streaming/video/decoder.h \
+    streaming/bandwidth.h \
     streaming/streamutils.h \
     backend/autoupdatechecker.h \
     path.h \