add debug feature, code cleanup

Merge pull request #7 from telit/feature/debug-and-cleanup

add debug feature for TLT class

Fix in ME310 library minimum release version

Merge pull request #5 from telit/fix/versioning

fix required minimum ME310 library version in readme

GNSS formatting utilities, better ME310 module management in sketches

Merge pull request #4 from telit/feature/GNSS

Add TLT GNSS example

add GNSS class

Merge pull request #1 from telit/feature/gnss-utils

add GNSS utility class, minor code cleanups