Fix for the char and string conversion compile errors present
Merge pull request #83 from anthony-ngu/FixSerialWriteCastIssues

Fix for the char and string conversion compile errors present
fix compilier warnings for radians() and float()
Replace Arduino supplied values with math.h values.
- PI, TWO_PI, HALF_PI
Resolved several /W4 warnings
Merge pull request #85 from zfields/develop

Resolved several /W4 warnings