Major plugin refactor and cleanup.

Switched to POCO library for unified platform/library interface.
Deprecated the external module API. It was creating more problems than solving.
Removed most built-in libraries in favor of system libraries for easier maintenance.
Cleaned and secured code with help from static analyzers.

vendor/POCO/NetSSL_Win/doc/README.txt

@@ -0,0 +1,69 @@
+About NetSSL_Win
+================
+
+NetSSL_Win is an implementation of the POCO NetSSL library based on Windows 
+Schannel. The original NetSSL implementation is based on OpenSSL and thus
+has a few OpenSSL-isms in the interface. Generally, source code based
+on NetSSL_OpenSSL can be easily ported to use NetSSL_Win. Just a few
+minor code changes are required, due to differences in the API. 
+These are discussed below:
+
+  - Context: The Context constructor uses different arguments. While
+    the first argument is the same, all others are different.
+    Instead of a certificate file name, a certificate subject name is
+    specified. Certificates can be loaded from a Windows
+    certificate store, or from PKCS #12 files (.pfx, .p12) containing
+    certificate and private key pairs, if the OPT_LOAD_CERT_FROM_FILE
+    is specified. In the latter case, a private key passphrase handler
+    must be setup.
+    Please refer to the header file documentation for more information.
+    Furthermore, the following Context methods are not available in NetSSL_Win:
+    addChainCertificate(), disableStatelessSessionResumption(), 
+    enableSessionCache(),flushSessionCache(),
+    getSessionCacheSize(), getSessionTimeout(),
+    setSessionCacheSize(), setSessionTimeout(), sslContext(),
+    useCertificate(), usePrivateKey().
+
+  - SSLManager: The configuration properties used to configure the SSLManager
+    are different from the ones used in NetSSL_OpenSSL. Please see the
+    SSLManager header file for more information. 
+    The isFIPSEnabled() method is not available.
+
+  - X509Certificate: Saving a certificate is not supported.
+
+
+Certificate and Certificate Stores
+----------------------------------
+
+The test suite and samples expect a certificate/private key file named
+any.pfx, located in the current working directory. This can be changed
+by editing the testrunner.xml/TestSuite.xml configuration files.
+Alternatively, a certificate from the Windows certificate store can be used.
+A suitable self-signed certificate can be created using the Windows 
+IIS administration console, then exported to a file, and re-imported into 
+the user's personal store.
+
+To create the certificate, follow these steps:
+
+  1. Launch the Computer Management utility.
+  2. Go to Services and Applications > Internet Information Server.
+  3. Open the Server Certificates feature.
+  4. Under Actions, click "Create Self-Signed Certificate...".
+  5. Enter a user-friendly name for the certificate.
+     The certificate will be issued to the name of your computer.
+  6. Export the certificate by right-clicking it and chosing "Export...".
+  7. In Explorer, double-click the exported certificate file (.pfx)
+     to launch the Certificate Import Wizard.
+  8. Import the certificate into your personal store by 
+     selecting "Place all certificates in the following store" and
+     selecting the "Personal" store in the import wizard.
+
+
+Windows Embedded Compact
+------------------------
+
+Windows Embedded Compact does not support the following Schannel
+features: 
+  - certificate revocation checking (Context::OPT_PERFORM_REVOCATION_CHECK)
+  - TLS 1.1 and 1.2 (Context::TLSV1_1_CLIENT_USE, etc.)
+  - disabling weak security algorithms (Context::OPT_USE_STRONG_CRYPTO)