minor webgl precision fixes + dispose webgl backends in between test …

minor webgl precision fixes + dispose webgl backends in between test suites to free up memory from cache

update to tfjs-core 1.0.3 + update dev dependencies

Update to tensorflowjs 1.0.1

remove 'baseUrl: .' from tsconfig, to prevent absolute file imports + replaced absolute file import in src

face expression recognition

implement drawFaceExpressions helper and use them in examples + nodejs face expression recognition example

refactored some stuff + train and test script for face expressions net with trained feature extractor