~ adopt comments

Conflicts:
	zh_CN.UTF-8/books/handbook/filesystems/chapter.xml
Merge pull request #7 from 0x02/upstream

~ adopt comments
Revised handbook/firewalls to r43126. Line 162, 3%.

NOTE: r43126 is the most recent revision from r43258.
Revised handbook/firewalls to r43126. Line 319, 7%.

Some indents are changed in keeping with original documents.
Revised handbook/firewalls to r43126. Line 487, 10%.

Copied around 1500 new lines in original revision and not all translated.
To be faithful to the original, I kept the trailing whitespace in original revision.
Also, I adjusted some indents.