Allow longer names (MAX_LAYER_NAME_LEN was 32, now 64)

[rxhfcy]

This trivial patch allows a little bit longer layer names (I think the maximum could easily be 128 or 256 but I chose to be very conservative to maximize the probability of you accepting the change).

The reasoning for allowing longer names is that it is conceivable that someone could try to use names more than 32 - 2 letters long (I already personally did that, wasn't even joking) (issue #558)

Furthermore, if someone uses their non-english native language with non-ASCII characters, 32 bytes is even more restrictive (32 bytes can hold even fewer than 32 longer-than-1-byte UTF-8 characters)

[rxhfcy]

@rvaiya Could you please consider accepting this trivial change that fixes a legitimate bug (#558)?

Reason: I legitimately (without irony or trying to be funny) tried to use a name that was exactly 1 character too long (33). Potentially other users would want to do that too, and keyd silently failing because of such a length is unreasonable.

Changing MAX_LAYER_NAME_LEN in src/config.h to even 64 instead of 32 would allow users to use slightly sillier names if they want to.