Doing so allows for building on webassembly. Officially declareing support for WASM
however will have to wait until https://github.com/pyodide/pytest-pyodide/pull/59 is
merged to facilitate testing WASM compatibility.
To fix issues with floating-point precision we've made use of Google's
double-conversion lib to handle conversions of doubles to and from strings.
In addition to fixing our precision problems this will improve double
encoding by 4-5x. Decoding is however slightly slower according to the
benchmarks - but accurate at least.
This change removes the double_precision encoding option and the
precise_float decoding option.