Update emscripten to 1.38.10

Use ccache to speed up rebuilds

MAINT Minor fixes in the Makefile for make clean

Decrease Python call stack size so it doesn't exceed JS call stack

Fix rebuilding of emsdk

Fix #80: Delete emsdk if rerunning make

Update link to recurse center code of conduct

Fix #78: LINT [skip ci]

Safer parsing of expression at end of code block

Don't copy data if already on the WASM heap

Add testing with Chrome