enhanced navigation in reference page
enhanced navigation in reference page

- added backlinks from detail headers to (table of) content entries
- enhanced #top link to select searchbox entry and focus on it
- made navigation jumps (former anchorlinks) to postion at 20% of view port
- made completed navigation jump to blush blue on back and gold on forward

- added htmldev development mode flag to develop and test in standalone mode

Changes to be committed:
	modified:   scripts/build_docs.py

nkolban/Espruino,muet/Espruino,muet/Espruino,wilberforce/Espruino,jasonkajita/Espruino,mjdietzx/Espruino,jasonkajita/Espruino,wilberforce/Espruino,nkolban/Espruino,nkolban/Espruino,wilberforce/Espruino,mjdietzx/Espruino,tve/Espruino,nkolban/Espruino,muet/Espruino,lancernet/Espruino,tve/Espruino,AlexanderBrevig/Espruino,AlexanderBrevig/Espruino,AlexanderBrevig/Espruino,AlexanderBrevig/Espruino,tve/Espruino,muet/Espruino,AlexanderBrevig/Espruino,jasonkajita/Espruino,nkolban/Espruino,jasonkajita/Espruino,tve/Espruino,jasonkajita/Espruino,mjdietzx/Espruino,wilberforce/Espruino,nkolban/Espruino,redbear/Espruino,luetgendorf/Espruino,lancernet/Espruino,luetgendorf/Espruino,luetgendorf/Espruino,nkolban/Espruino,jasonkajita/Espruino,luetgendorf/Espruino,muet/Espruino,mjdietzx/Espruino,luetgendorf/Espruino,redbear/Espruino,lancernet/Espruino,redbear/Espruino,wilberforce/Espruino,lancernet/Espruino,AlexanderBrevig/Espruino,mjdietzx/Espruino,redbear/Espruino,tve/Espruino,mjdietzx/Espruino,lancernet/Espruino,redbear/Espruino,mjdietzx/Espruino,luetgendorf/Espruino,muet/Espruino,jasonkajita/Espruino,redbear/Espruino,wilberforce/Espruino,redbear/Espruino,muet/Espruino,lancernet/Espruino,tve/Espruino,luetgendorf/Espruino,tve/Espruino,wilberforce/Espruino,lancernet/Espruino