startTransmit make data arg constant

[dizcza]

All startTransmit functions should accept the constant uint8_t* data.

I've gone through their implementation but am still not sure if I can safely cast my constant data buffer to be modifiable and expect that it won't be changed inside the startTransmit functionality.

[jgromes]

No modifications to the user buffer are done within startTransmit, so yes, const uint8_t* data is the more proper way to go.

[jgromes]

Added in the mentioned commit - this is likely going to cause a new minor release as the public API has changed in a way that may throw some people off.