Fixed issue #1382

- Ashtech driver is no longer checking fix status from comparing
  coordinates to 0.0;0.0;0.0, instead it's checking fix type in GGA or
  checking coordinate exsistance in POS. This removes compiler warning
  about float euqality comparison.

- Fixed compiler warning about comparison between signed and unsigned
  int

- Fixed compiler warning about class property masking
Checking if fix status is less or equal to 0 rather than just equal
Merge pull request #1384 from dyeldandi/issue_1382

Fixed issue #1382