mbedTLS version 2.1.0 (current stable)
Has some known issues/hacks:
* Entropy source not hooked in at all
* Linker script has a messy hack in it to store some (not all) data in
irom
This fixes a long-standing bug where build directories sometimes
expanded many levels deeper than they should have.
Component names can now no longer contains slashes (ie the component
name for 'extras/i2c' is now just 'i2c')