[Feature] Optionally exclude debug logging from object code

[tonhuisman]

Resolves: #7

Optionally leave out the debug logging (and the somewhat long flash-string messages) to reduce sketch size (ca. 0.5 kB gained).

Usage:

• Uncomment this line // #define MAX1704x_ENABLE_DEBUGLOG 0 (ca. line 26 in SparkFun_MAX1704x_Fuel_Gauge_Arduino_Library.h) to disable the debug logging
• or: Add -DLIBRARIES_NO_LOG=1 to your compiler build flags to disable debug logging
• or: Use library as before to keep the debug logging in

[PaulZC]

Thank you Ton (@tonhuisman ),

Merging into release_candidate for testing...

Best wishes,
Paul