PIO compiler warnings fix

Merge pull request #3 from bogde/master

Merge pull request bogde#233 from nschurando/master

Update version number to 0.7.5

Update version number in library.properties

Merge pull request bogde#155 from r-a-i/readme_patch

Fix variable name in README.md example code

Version 0.7.2

Stable version, after spring cleaning.

Working version, before the 2019 spring cleaning.

Merge pull request bogde#9 from Deamiter/patch-1

Fixed typo in scale calibration instructions.