[Feature] Optionally exclude debug logging from object code

[tonhuisman]

Resolves #3

Optionally leave out the debug logging (and the somewhat long flash-string messages) to reduce sketch size (ca. 2.5 kB gained).

Usage:

• Uncomment this line // #define SCD4x_ENABLE_DEBUGLOG 0 (ca. line 33 in SparkFun_SCD4x_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 😃