Increased mime base64 encoding speed to the max by implementing 12-bit lookup for decoding 2 base64 characters at a time.  Re-ran all tests.  This should compete with the fastest mime base64 encoders available anywhere at a fraction of the code size and with Apache2 license and unencumbered.
Increased mime base64 encoding speed to the max by implementing 12-bit
lookup for decoding 2 base64 characters at a time.  Re-ran
all tests.  This should compete with the fastest mime base64 encoders
available anywhere at a fraction of the code size and with Apache2 license
and unencumbered.

ddysher/turbo,ddysher/turbo,luastoned/turbo,zcsteele/turbo,zcsteele/turbo,mniestroj/turbo,kernelsauce/turbo,YuanPeir-Chen/turbo-support-mipsel,luastoned/turbo,YuanPeir-Chen/turbo-support-mipsel