Simple style fix

[xiaoxiang781216]

• remove the unnecessary header file inclusion
• replace all time_ with time
• correct the comment for minmea_scan and minmea_tocoord
• change the sentence code in alphabetical order

[kosma]

These are a bit more controversial:

1. Unneccessary file inclusion - correct, merged
2. Replace time_ with time - this is to avoid shadowing time() from time.h which can cause warnings under some compilers.
3. Correct the comment - I've corrected the comment for minmea_scan(). The comment for minmea_tocoord() is correct - it converts from the internal DDMM.MMMM (degrees + fractional minutes) representation into a degrees-only fractional (float).
4. Reordering the code - this brings no functional change but destroys git history so sadly I can't accept this.

Overall - I've used two of the four commits. Thanks for the contribution!

Merged here: https://github.com/kosma/minmea/commit/296c71cbc00f7ba9e0758d83ee95d959b84655cc