Issues with including .hh and .hpp files

[per1234]

I am merging two related issues and moving them here from the IDE repository at the request of facchinm:

Moved from arduino/Arduino#5441:

Using Arduino IDE 1.6.13 Hourly Build 2016/10/03 06:51 with Windows 7 64 bit

arduino/Arduino#3186 added support for including .hpp and .hh files from libraries.

If I have a library installed with the folder structure:

foo
|_foo.h
|_foo.hh
|_foo.hpp

With Arduino IDE 1.6.6 or newer, doing:

#include <foo.hh>

or

#include <foo.hpp>

causes compilation to fail:

fatal error: bar.hh: No such file or directory
 #include <foo.hh>

It will only compile if I do:

#include <foo.h>
#include <foo.hh>

Using Arduino IDE 1.6.5-r5 I don't need to include the .h file.

---

### Moved from https://github.com/arduino/Arduino/issues/5442:

Using Arduino IDE 1.6.13 Hourly Build 2016/10/03 06:51 with Windows 7 64 bit

@Chris--A added support for .hh and .hpp sketch files in arduino/Arduino#3485 however if I create a sketch tab with a .hh extension and then try to include that file from the sketch:

#include "hhtab.hh"

compilation fails:

fatal error: hhtab.hh: No such file or directory
 #include "hhtab.hh"

This problem doesn't occur with sketch tabs with the .hpp extension.

Originally reported at http://forum.arduino.cc/index.php?topic=427309