Polina Goltsman nits

- Various typos.
Polina Goltsman issue 12

"sec. 3.1
========
old:
   o  To determine its position in the overlay topology (if the overlay
      is structured; topology plugins do not need to be structured).
new:
   o  To determine its position in the overlay topology (if the overlay
      is structured; overlays do not need to be structured).

a structured topology plugin is not the same as a structured overlay"

- As suggested.
Polina Goltsman issue 13

"old:
   The general principle here is that the security mechanisms (TLS at
new:
   The general principle here is that the security mechanisms ((D)TLS
at"

- s/TLS/TLS or DTLS/
Polina Goltsman issue 14

"sec. 3.2.1
==========
      clients that choose this option need to process Update messages

Update messages are not introduced yet, so a forward reference to
section 6.4.2.3 would be helpful"

- As suggested.
Polina Goltsman issue 15

"Furthermore, the reference to Section 6.5.1 should be moved
to the previous sentence."

- As suggested.
Polina Goltsman issue 16

"old:
   This section will discuss the capabilities of RELOAD's routing layer,
new:
   This section discusses the capabilities of RELOAD's routing layer,"

- As suggested.
Merge pull request #226 from petithug/polina-goltsman-nits

Polina Goltsman nits
Merge pull request #222 from petithug/polina-goltsman-issue-16

Polina Goltsman issue 16
Merge pull request #221 from petithug/polina-goltsman-issue-14

Polina Goltsman issue 14
Merge pull request #220 from petithug/polina-goltsman-issue-13

Polina Goltsman issue 13
Merge pull request #219 from petithug/polina-goltsman-issue-12

Polina Goltsman issue 12
Merge pull request #223 from petithug/polina-goltsman-issue-15

Polina Goltsman issue 15
update date