Fix clang warnings and run clang-format
Fix clang warnings and run clang-format

Clang warnings:
./lib/NMEAParser.cpp:25:8: warning:
no previous prototype for function 'faster_mktime' [-Wmissing-prototypes]
time_t faster_mktime(struct tm *tm) {
       ^
../lib/NMEAParser.cpp:28:54: warning:
missing field 'tm_gmtoff' initializer [-Wmissing-field-initializers]
  static struct tm cache = {0, 0, 0, 0, 0, 0, 0, 0, 0};

* Add static to faster_mktime
* Change initialiser list to {} for cache

NeuralSandwich/NMEAParser,NeuralSandwich/NMEAParser,NeuralSandwich/NMEAParser,NeuralSandwich/NMEAParser