* 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
* New "espefuse.py set_flash_voltage" command to easily set a fix
VDD_SDIO regulator voltage (1.8V, 3.3V or disabled).
* Fixes bugs when flashing files with non-4-byte aligned lengths
(doesn't effect esp-idf image files)
* README improvements
