Update Mono.Security.dll assembly to Mono version 3.4.0

Fix #264
Add tests for float4 and float8 NaN inserting.
Fix #217 when handling NaN for float4 and float8 datatypes.

After commit 854862aeb4ba2c7f6d6cd321baeddbddbeca74fd Npgsql wasn't
adding quotes around float4 and float8 values.

But according to documentation, NaN values need to be quoted.

Separated handling of float4 and float8 conversion routines.
Add support to handle NaN values inside arrays. Thanks @glenebob for heads up.

Add tests for Float array.
Remove Tools/vssdk*_tools/inc folder.

This folder contains only .h files which aren't used by Npgsql and takes a large space.
Repro unit test for #296
Remove Postgresql 8.4. from unit tests

Fixes #297
Unit test for #158 (prepared stmt leak)
Deallocate prepared statement on Dispose()

Note that this only happens in explicit Dispose()/
using, and not when Dispose() is called from a
finalizer (implementation for that is complicated).

Regardless, all prepared statements are automatically
deallocated when a connection is returned to the
connection pool (DISCARD ALL).

Fixes #158
Prevent another prepared stmt leak

When a prepared command is re-prepared, the first
backend statement was not deallocated.

Noticed by @franciscojunior
Merge pull request #299 from roji/deallocate_prepared

Fix prepared statement leaks
Cleanup for pre-9.0 checks and branches

Starting 2.3 we only support 9.0 and above, removed
checks and conditions for older versions
(mainly in the tests)
Added [MinPgVersion] attribute to unit tests

Checks the version and ignores the test if the backend
is too old. Replaced manual checks.
Merge pull request #273 from franciscojunior/264-update-Mono-Security

Update Mono.Security.dll assembly to Mono version 3.4.0
Merge branch 'bug296' of https://github.com/roji/Npgsql into bug_296
Simplfied repro unit test bugs #240 and #296

This is about as simple as I can make it.
Fix for bugs #240 and #296

Properly handle escaped single quote character ('') in a quoted section during query parameter substitution.
Bugs #249 and #296 Unit Test Improvements

Use close approximations to the repro queries supplied for these bugs, in addition to the simple one devised for diagnosis.
Merge pull request #257 from franciscojunior/217-fix-doubleNaN-regression

Fix #217 double NaN regression
Remove debug/logging code.