* Philosophical: "explicit is better than implicit".
* Practical: Allows useful errors if invalid directories given in components as the defaults aren't
always used. Also trims the -I path from a number of components that have no actual include
directory.
* Simplifies knowing which components will be header-only and which won't
* Change snprintf for strlcat does not complain w/gcc7.2.0 and it is safer, thanks @projectgus
* Use proper quotes for character literals
Merges https://github.com/espressif/esp-idf/pull/1163
Old behavior assumes message compressed when any of 2 most significant bits are set,
But in fact Message compressed only when both those bits are set to 1.
Also maximal label length should be 63 bytes.
