Added parentheses to macros, so that best-practices
with C macros are followed, in RDUtil.h.
Fixed up confusion in README
Joined two recommendations together regarding the
naming of header files and functions.
Added a recommendation that all header files
should end with an empty line.
Added macros and updated Analoginit, AnalogRead.

Added useful macros for setting the ADC prescaler.
Added setting Vref to external in RDAnalogInit().
Slight format changes to RDAnalogRead().
Added RDAnalogContRead().

New function to enable/disable free running mode of the ADC.
Merge pull request #10 from ShaunKarran/Shaun/New

Shaun/new