History of A re-introduction to JavaScript (JS tutorial)

Fix doc test tool discovered bugs - woot!

Fixes to handling of octal/hex (octal parsing w/o radix parameter is gone, hex is not). Other content cleanup.

Discussion about memory leaks is inappropriate to an introduction, and the information that was there was semi-obsolete.

welcome to surrogate pairs, the outer circle of hell

unary + operator honors hexadecimal

The end parameter for Array.slice is optional.