tag v0.13.0-alpha3

tag v0.13.0-alpha2

tag v0.13.0-alpha1

add debug.FormatMsg

go.mod: update serport dependency, which adds arm64 and Linux' serial…

…_rs485 support

rtu/readmgr: use 256 byte buffer, rather than 64

did: propagate request Options

register/regtype: add lb.go (forgotten)

register/regtype: typeSpec: new byteOrder suffixes le, lb

le: little Endian
lb: little Endian, bytes swapped

go.mod: update