Faster cmake compilation (parallel) + removed warnings

[antonio-leblanc]

faster build

added options to cmake

# 3. Build in parallel on all cores
cmake --build build -- -j"$(nproc)"

removed warnings

added 3 returns here...

	double getWidth(){ return baseLayer->getWidth(); };
	double getHeight(){ return baseLayer->getHeight(); };
	double getDepth(){ return baseLayer->getDepth(); };

Adding badges on readme