Moving to ESP-IDF release 3.0, and some Bluetooth, and ....

@Wilberforce, thanks for your feedback

• So we have agreement for removing OTA, great.
  
• I've seen, you already created an espv3 branch. Would it be correct, to change line 3 to v3 and line 4 to esp32 branch in build-idf.sh ? I will do my best to bring up a version. Pretty sure, I've to contact you to get a better understanding of BuildTool. For example, right now, I've no idea how to test my changes.
  
• For compiling we will need a new compiler version. How/where would we tell which compiler to use ?
  
• with/without BLE is a problem. Creating 2 firmware binaries would mean 2 different precompiled templates, more maintenance, etc. etc. An option to switch BLE on/off during runtime would not help, since we would need a kind of jsVar-renumber to increase or decrease number of jsVars.
  
• and, number of jsVars, hmm, using V3 already eats a lot of RAM, much more than V2.1. My assumption is, maximum will be somewhere between 3500 and 4000 jsVars. If there is anybody interested in that and having the time to check this seriously, please go ahead and give us some feedback.
  
• BTW, do you have experience with Gordons point to upload code directly to flash ?
  
• I had a big discussion with Gordon in Nürnberg. He has a great idea, how to reduce RAM usage for jsVars and store them in Flash. This is future talk, but will be a big step.