don't touch addressbook when using secure payment-requests

- fixes #3006 by preventing addressbook changes when using
  secure payment-requests

sq
Update michagogo's gitian pgp key, adding UIDs
Documentation Cleanup in /Doc

Added some help text, and bumped version numbers.

Added a Readable Index for /Contrib

Fixing /Contrib Index URLs

Revert Version Numbers.
make BitcoinAmountField::setReadOnly() usable

- use it for secure payment-requests (this change allows a copy&paste of
  the amount and looks a little nicer than just a disabled GUI element)
doc: remove readme-qt.md

Now that autotools is used as a build system there is nothing
special about building the GUI anymore. Merge the salvageable
parts into build-unix.md
doc: build with qt5 is currently not possible

Add as a separate commit so that it can be easily reverted once
Qt5 is supported again.
Merge pull request #3083 from sipa/chainlocator

CBlockLocator improvements & move to core
Merge pull request #3092 from laanwj/2013_10_remove_readme_qt

doc: remove readme-qt.md
Merge pull request #3086 from Michagogo/update-pgp

Update michagogo's gitian pgp key, adding UIDs
Merge pull request #3085 from super3/master

Documentation Cleanup and Contrib Index
Broken Link in /Doc README

#3092 removed readme-qt.md, but it was still listed in the index for the /doc README.
Merge pull request #3097 from super3/master

Broken Link in /Doc README
Finished /Contrib Index. Standardized READMEs.

File and Link Fix.
Merge pull request #3094 from Diapolo/btcamountfield

make BitcoinAmountField::setReadOnly() usable
Merge pull request #3069 from Diapolo/fix_addressbook

don't touch addressbook when using secure payment-requests
Merge pull request #3098 from super3/master

Finished /Contrib Index. Standardized READMEs.
Do not use the redundant BestInvalidWork record in the block database.

As block index entries have a flag for marking invalid blocks, the
'best invalid work' information can be derived from there. In addition,
remove the global from main.h
Make some globals in main non-public.

This means they are declared static, and their extern definition in
main.h is removed. Also moved CBlockIndexWorkComparator to the .cpp
file.