Emscripten builds for web apps

Crosscompiling MRPT to a JS library

Install Emscripten: https://emscripten.org/docs/getting_started/downloads.html

cd mrpt
mkdir build-ems
cd    build-ems

cmake .. \
  -DCMAKE_TOOLCHAIN_FILE=$HOME/code/emsdk/upstream/emscripten/cmake/Modules/Platform/Emscripten.cmake \
  -DMRPT_EIGEN_USE_EMBEDDED_VERSION=ON \
  -DMRPT_HAS_OPENNI2=OFF \
  -DMRPT_AUTODETECT_SIMD=OFF

make