We now use a stack allocator when making a copy of current connection state at
the start of the signal emission process, and when collecting results from
signal handlers in the case of a non-void return type.
These changes also include a functionally neutral reworking of how the connection
state copy is made and then used to check that a connection/handler is still
valid mid-emission.
Heap allocation will still happen if a signal has more than (currently) 512
connections. A little experimentation reveals that the maximum number of
connections is typically nroutes+1, so 512 seems like a reasonable choice
for this.
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