async+perf: appendix-B, adding more to 'iterable sequences' section
async+perf: appendix-B, more clarifications and discussion of promise vs iterable sequence
types+grammar: minor typo fix
types+grammar: ch4, clarifying some details around == unboxing, per #233
Fill in missing chapter number
async+perf: clarifications to appendix-B wording
Merge pull request #236 from 4thana/patch-3

Fill in missing chapter number
add missing parameter "delay" to timeoutify call
fix variable name in comment
Merge pull request #238 from 4thana/patch-4

add missing parameter "delay" to timeoutify call
Merge pull request #239 from 4thana/patch-5

fix variable name in comment
async+perf: appendix-B, adding 'event reactive' section