Proposed: disallow leading zeros in some parts of float numeric representation

[DeLaGuardo]

Based on https://ask.clojure.org/index.php/14798/clojure-edn-leading-zeros-in-numbers

Fractional and exponent parts of a float allow literal zero to be represented using any number of \0 digits. This might be used to slow down any edn parser when supplied edn contains numbers like this: 0.0e000....0 (really a lot of zeros).