Reduce the memory usage of ConnectinClass objects by changing their large
 fixed length text fields to variable ones. Because changes are applied to
 percent-encoded fields this time, password field is also a target of this
 change.
Revise MSDTC support.
1. Remove pointlessly complicated AsyncThreads stuff. Instead use
   _beginthread() to clean up threads.
2. Make pgenlist.dll from the structure change of ConnectionClass.
   The driver dlls exports the functions described in connexp.h
   which are used by pgenlist.dll.

3. Isolate the current communication path if necessary.
   While an IAsyncPG object is alive, a ConnectionClass object (hereinafter
   refered to as conn-obj) is assigned to it. The assignment has to be
   changed in the following cases.

   a) SQLDisconnect() is called for the current connection handle which
      is assigned to an IAsyncPG object.
	Allocate another conn-obj and move the current communication
	path (*sock* member of the current conn-obj) to the new conn-obj.
	The communicaation path is lost from the current conn-obj and
	the new conn-obj is assigned to the IAsyncPG object.

   b) Another (global) transaction is about to begin but the current
      global transaction is not PREPARED yet.
	Same as case a) but will open a new communication path for
	the current conn-obj for the subsequent ODBC API calls.

   c) Another (global) transaction is about to begin and the current
      global transaction is already PREPARED.
	Allocate another conn-obj and open a new communication path for
	the conn-obj. The new conn-obj is assigned to the IAsyncPG
	object only to issue COMMIT/ROLLBACK PREPARED command.

   communication pass (*sock* member of the current ConnectionClass
   object) to the new object and change the state of the current
   object NOT CONNECTED. The IAsyncPG object uses new object instead
   of the current object. In case b) the current object will open a
   new communication path.
Ignore automatically-generated files in source code with .gitignore.
This is useful to prevent accidental commit of files that are not wanted
in the remote repository. The original patch was provided by Michael
Paquier. I also added files genearated by VC build tools or WIX tools
to .gitignore.
Change configure.ac so that ODBC_CONFIG is set when neither unixODBC nor
iODBC is explicitly specified.
The first cut of psqlodbc setup project. It builds a setup program which
can't be done by a single MSI. It would install VC++ redistributable, 32
bit psqlodbc driver and 64 bit psqlodbc driver (on 64 bit windows).
Configure is checking SIZEOF_LONG not SIZEOF_LONG_INT.