Added wrapper functions to read flags

ReefAngel.h - Added wrapper functions declaration
ReefAngel.cpp - Added wrapper functions implementation
ReefAngel_1.5_LCD.h - Refactored to make use of the new functions

*boolean ReefAngelClass::isLeak() only visible #ifdef LEAKDETECTOREXPANSION
*boolean ReefAngelClass::isBusLock() only visible #ifdef BUSCHECK