Includes all the latest NimBLE stack changes from idf-v4.0 with few idf-v3.3
specific modifications.
- Addition of nimble component as submodule (`nimble-1.1.0-idf-v3.3`), contains
IDF v3.3 specific minor changes.
- Example applications are identical to idf-v4.0
- Modification in `bt/Kconfig` to accommodate NimBLE as a BT host.
* Use "example" in all example function & variable names,
ie use i2c_example_xxx instead of i2c_xxx for example functions.
Closes#198https://github.com/espressif/esp-idf/issues/198
* Mark example functions, etc. static
* Replace uses of "test" & "demo" with "example"
* Split the UART example into two
* Rename "main" example files to end with "_main.c" for disambiguation
