STP_Whistle

Updates:
-Narrow flip holes and wider chambers (harder to "over blow")
-Internal support.

Based on Fox 40 whistle 3 chambers design
-LP_LC NH version: lower pitch (around 3200Hz) and chambers with larger diameters than original Fox 40.
-HP_Fox_40_LC NH version: pitch very similar to Fox 40 and chambers with larger diameters.
-HP_Fox_40_LC NH 1.3 version: pitch even closer to Fox 40 and chambers with larger diameters. To print: do no use "Detect thin walls" (or any similar function) on Sl