Updated json to correctly handle double and float nan
Updated json to correctly handle double and float nan

Previously a double nan was serializing to the string "nan" which is invalid JSON.

Updated to use undefined instead of nan for both serializing and deserializing.

Rationale:

ECMA-262 states "The undefined value is [...] used when a variable has not been assigned a value", while "The null value [...] represents the null, empty or non-existent reference."

While I was at it, cleaned up incorrect grammar and spelling mistakes.

schuetzm/vibe.d,DBankov/vibe.d,ColdenCullen/vibe.d,etcimon/vibe.d,rejectedsoftware/vibe.d,etcimon/vibe.0,sigod/vibe.d,sigod/vibe.d,etcimon/vibe.0,Kozzi11/vibe.d,alphaKAI/vibe.d,Mihail-K/vibe.d,etcimon/vibe.d,fast4shoot/vibe.d,alphaKAI/vibe.d,alphaKAI/vibe.d,veelo/vibe.d,Yoplitein/vibe.d,chalucha/vibe.d,nathanchristenson/vibe.d,nathanchristenson/vibe.d,machindertechnologies/vibe.d,sigod/vibe.d,mfrischknecht/vibe.d,AndreyMZ/vibe.d,Geod24/vibe.d,gedaiu/vibe.d,redstar/vibe.d,nathanchristenson/vibe.d,Yoplitein/vibe.d,yannick/vibe.d,Yoplitein/vibe.d