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/Data/PostgreSQL/include/libpq/libpq-fs.h

@@ -0,0 +1,24 @@
+/*-------------------------------------------------------------------------
+ *
+ * libpq-fs.h
+ *	  definitions for using Inversion file system routines (ie, large objects)
+ *
+ *
+ * Portions Copyright (c) 1996-2015, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * src/include/libpq/libpq-fs.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef LIBPQ_FS_H
+#define LIBPQ_FS_H
+
+/*
+ *	Read/write mode flags for inversion (large object) calls
+ */
+
+#define INV_WRITE		0x00020000
+#define INV_READ		0x00040000
+
+#endif   /* LIBPQ_FS_H */