Spelling fixes.

Spelling fixes in Chapter 2.
Some changes in Chapter 3
Merge pull request #32 from escalant3/chapter3-fixes

Some changes in Chapter 3
Merge pull request #31 from andrewSC/master

README.md: Correcting punctuation
Merge pull request #30 from Xumeiquer/master

Spelling fixes.
Typo: access -> accessed
Typo: base->lucid32

the box name 'base' is different from 'lucid32' in Vagrantfile, which causes download box twice, one time for 'vagrant add box' another time for 'vagrant up'
Merge pull request #35 from mslevin/patch-1

Typo: access -> accessed
Merge pull request #36 from neilss/master

Typo: base->lucid32
Update README.md

Explain ascii codes
Update README.md

fix spacing
Merge pull request #37 from zachriggle/master

Explain putc() special characters
Chapter-6/README.md: minor typo
Merge pull request #40 from dharmatech/patch-1

Chapter-6/README.md: minor typo
Added next/previous links to all chapters
Fix #39
Merge pull request #41 from bbaugher/master

Added next/previous links to all chapters
Translate some comments
Add base code for idt gestion
Translate some comments