update getnetworkinfo help with subversion

- add missing subversion field to getnetworkinfo help
- fix style and format errors in help string
- remove unneeded int casts
CBufferedFile: convert into a non-refcounted RAII wrapper

- it now takes over the passed file descriptor and closes it in the
  destructor
- this fixes a leak in LoadExternalBlockFile(), where an exception could
  cause the file to not getting closed

- disallow copies (like recently added for CAutoFile)
- make nType and nVersion private
CBufferedFile: add explicit close function

- also use identical close function for CAutoFile (avoids setting file to
  NULL under wrong conditions)
CAutoFile: make file private
Correct logging AcceptBlock()->AcceptBlockHeader()
depends: disable unused bdb replication manager. Fixes new mingw builds

Newer mingw supports the features necessary to enable this api, whereas older
versions didn't. However once enabled (automatically by configure), it triggers
an unrelated build bug.

Since it was not enabled previously anyway, and we don't depend on the
functionality, just disable it across the board.
Merge pull request #5034

609adc7 depends: disable unused bdb replication manager. Fixes new mingw builds (Cory Fields)
DRY: Avoid repetitions in script_test
Merge pull request #4978

938bcce CAutoFile: make file private (Philip Kaufmann)
0c35486 CBufferedFile: add explicit close function (Philip Kaufmann)
c9fb27d CBufferedFile: convert into a non-refcounted RAII wrapper (Philip Kaufmann)
Merge pull request #4994

54510f2 DRY: Avoid repetitions in script_test (jtimon)
Merge pull request #4887

4bb30a1 Correct logging AcceptBlock()->AcceptBlockHeader() (R E Broadley)
Merge pull request #4982

b5ec5fe update getnetworkinfo help with subversion (Philip Kaufmann)
Headers-first synchronization

Many changes:
* Do not use 'getblocks', but 'getheaders', and use it to build a headers tree.
* Blocks are fetched in parallel from all available outbound peers, using a
  limited moving window. When one peer stalls the movement of the window, it is
  disconnected.
* No more orphan blocks. At all. We only ever request a block for which we have
  verified the headers, and store it to disk immediately. This means that a
  disk-fill attack would require PoW.
* Require protocol version 31800 for every peer (released in december 2010).
* No more syncnode (we sync from everyone we can, though limited to 1 during
  initial *headers* sync).
* Introduce some extra named constants, comments and asserts.
RPC additions after headers-first
Remove CheckMinWork, as we always know all parent headers
Improve getheaders (sending) logging
Better logging of stalling
Add height to "Requesting block" debug