Stack overflow

Hi,
nmea 0.0.7 chokes with Stack Overflow on this data dumped from the GPS integrated into the Algiz tablet:

```nmea
$GNVTG,,,,,,,,,N*2E
$GNGNS,181604.00,,,,,NN,00,99.99,,,,*59
$GNGGA,181604.00,,,,,0,00,99.99,,,,,,*72
$GNGSA,A,1,,,,,,,,,,,,,99.99,99.99,99.99*2E
$GNGSA,A,1,,,,,,,,,,,,,99.99,99.99,99.99*2E
$GPGSV,4,1,13,02,35,291,,03,09,129,,05,14,305,,06,38,226,*7D
$GPGSV,4,2,13,07,56,177,,09,70,067,,16,20,055,,23,41,076,*77
$GPGSV,4,3,13,26,10,030,,29,05,341,,30,26,199,,36,30,158,*7E
$GPGSV,4,4,13,49,32,192,*4D
$GLGSV,3,1,10,66,45,091,,67,67,334,,68,17,297,,75,13,025,*68
$GLGSV,3,2,10,76,49,059,,77,40,156,,78,00,183,,82,15,246,*68
$GLGSV,3,3,10,83,28,298,,84,10,352,*6F
$GNGLL,,,,,181604.00,V,N*5E
$GNGRS,181604.00,1,,,,,,,,,,,,*5A
$GNGRS,181604.00,1,,,,,,,,,,,,*5A
$GNGST,181604.00,0.0000,,,,5773795,5773795,5773794*4F
$GNZDA,181604.00,12,09,2018,00,00*73
$GNGBS,181604.00,,,,,,,*7B
$GNTXT,01,01,02,u-blox AG - www.u-blox.com*4E
$GNTXT,01,01,02,HW UBX-M8030 00080000*60
$GNTXT,01,01,02,EXT CORE 3.01 (107900)*33
$GNTXT,01,01,02,ROM BASE 3.01 (107888)*25
$GNTXT,01,01,02,FWVER=SPG 3.01*46
$GNTXT,01,01,02,PROTVER=18.00*11
$GNTXT,01,01,02,MOD=NEO-M8N-0*67
$GNTXT,01,01,02,FIS=0xC22536 (100111)*28
$GNTXT,01,01,02,GPS;GLO;GAL;BDS*77
$GNTXT,01,01,02,SBAS;IMES;QZSS*49
$GNTXT,01,01,02,GNSS OTP=GPS;GLO*37
$GNTXT,01,01,02,LLC=FFFFFFFF-FFFFFFED-FFFFFFFF-FFFFFFFF-FFFFFF69*23
$GNTXT,01,01,02,ANTSUPERV=AC SD PDoS SR*3E
$GNTXT,01,01,02,ANTSTATUS=OK*25
$GNTXT,01,01,02,PF=3FF*4B
$GNVTG,,,,,,,,,N*2E
$GNGNS,181605.00,,,,,NN,00,99.99,,,,*58
$GNGGA,181605.00,,,,,0,00,99.99,,,,,,*73
```