strip out checks for repeated keys in generated json. no one cares
about repeated keys
reorder parser clauses and simplify escaping for performance
build maps immediately when returning maps instead of building a
proplist and converting
skip redundant check for `uescape` escaping
certain astral plane json escape sequences were inadvertently being
replaced with the replacement character
Merge tag 'v2.3.1' into develop

Conflicts:
	README.md
decoder clause reordering and unrolling to reduce `when` clauses
further unrolling of string parsing states and elimination of `when`
guards
switch to iodata accumulation for number parsing
early exit from value when encountering literals and less list allocation
for number parsing
less list allocation in `jsx_to_term`
remove `package.exs`, use `mix` branch instead
binary_to_whatever is not available on R15? fixed
extend `binary_to_whatever` to R14 even though it's not really supported
anymore
actually i can use flatten in `jsx_to_term`! sweet
produce binaries in escaped strings in decoder/parser instead of lists
switch to a counting implementation of number parsing a la strings
revert a `jsx_to_term` optimizatin that micro benchmarked well but didn't macro
benchmark well
disable maps on R14, R15 and R16
v2.4.0