offer verbose and terse versions of AUnit.h

[bxparks]

Current version leaves out the lhs and rhs strings of various assertXxx() statements, saving about 30-50% flash memory compared to ArduinoUnit. But these strings are actually very useful for debugging. Considering adding them back in, but offer 2 headers for the end-user:

• AUnit.h (contains lhs and rhs strings)
• AUnitTiny.h (AUnitShort.h, AUnitTerse.h?), which don't have these strings

Since these assertXxx() methods are actually#define macros, it should be possible to allow the user to select the version at compile time, and the linker should remove all the methods which aren't used by the given program. This allows the user to choose to pay for the flash memory or not, depending on the project. (Many of my unit tests hit close to 30kB even without the lhs and rhs strings).