Patch etrex 20to30

FIRMWARE 2.87 Beta (offset Fw_all.bin)

OLD NEW
10A546: 18 40
10A547: 70 1C
10A549: 78 70

FIRMWARE 2.87 Beta (offset *.gcd)

OLD NEW
18C7F1: 18 40
18C7F2: 70 1C
18C7F4: 78 70