Parser function for floating point hexadecimals

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> A JavaScript function to parse floating point hexadecimals as defined by the WebAssembly specification.

# Usage

import parseHexFloat from '@webassemblyjs/floating-point-hex-parser'
parseHexFloat('0x1p-1') // 0.5
parseHexFloat('0x1.921fb54442d18p+2') // 6.283185307179586

# Tests

This module is tested in two ways. The first one is through a small set of test cases that can be found in test/regular.test.js. The second one is non-deterministic (sometimes called fuzzing):

1. Generate a random IEEE754 double precision value `x`.

1. Compute its representation `y` in floating point hexadecimal format using the C standard library function `printf` since C supports this format.

1. Give both values to JS testcase and see if `parseHexFloat(y) === x`.

By default one `npm test` run tests 100 random samples. If you want to do more, you can set the environment variable `FUZZ_AMOUNT` to whatever number of runs you'd like. Because it uses one child process for each sample, it is really slow though. For more details about the randomized tests see the source.

# Links

- maurobringolf.ch/2017/12/hexadecimal-floating-point-notation/
- github.com/xtuc/js-webassembly-interpreter/issues/32
- github.com/WebAssembly/design/issues/292