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/SevenZip/Makefile

@@ -0,0 +1,34 @@
+#
+# Makefile
+#
+# Makefile for Poco SevenZip
+#
+
+include $(POCO_BASE)/build/rules/global
+
+objects = \
+	Archive \
+	ArchiveEntry \
+	7zAlloc \
+	7zBuf \
+	7zBuf2 \
+	7zCrc \
+	7zCrcOpt \
+	7zDec \
+	7zFile \
+	7zIn \
+	7zStream \
+	Bcj2 \
+	Bra \
+	Bra86 \
+	CpuArch \
+	Lzma2Dec \
+	LzmaDec \
+	Ppmd7 \
+	Ppmd7Dec
+
+target         = PocoSevenZip
+target_version = $(LIBVERSION)
+target_libs    = PocoFoundation
+
+include $(POCO_BASE)/build/rules/lib