sendcoinsentry: small clear() and setValue() changes

- clear(): clear all UI elements (for secure and insecure payments)
- setValue(): only modify UI elements, which need to be set (for secure
  or insecure payments)
sendcoinsdialog: display real failed address string

- display the real string (faulty address), which causes the valid address
  check to fail, instead of a stringified "nonsense" CBitcoinAddress
paymentserver: use own HTML-esc / add new header const

- make processPaymentRequest() use our own HTML-escaping function from
  GUIUtil
- make string "application/bitcoin-payment" a constant (below similar
  constant strings in the .cpp file)
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.
Reimplement CBlockLocator's chain-related logic in CChain.

This removes a few unused CBlockLocator methods, and moves the
construction and fork-finding logic to CChain (which can do these
more efficiently, as it has a height-indexable chain available).
It also makes CBlockLocator independent from the validation code.
Move CBlockLocator to core.h

As CBlockLocator is a P2P data structure, and independent from the
validation logic, it can be moved to core.
replace %zu with %"PRIszu" macro to prevent compiler warnings
Merge pull request #3093 from Diapolo/printf_format

replace %zu with %"PRIszu" macro to prevent compiler warnings
Merge pull request #3080 from Diapolo/sendcoins-paymentreq

Bitcoin-Qt: misc changes for sendcoins and paymentsever
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)
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
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