Add OTR support.

This patch adds support for the OTR protocol to irssi. This is an import
of the external irssi-otr project that we are now taking over
maintership for.

Major thanks to the original authors of Irssi-OTR: Uli Meis and David
Goulet. Thanks to the OTR community in #OTR on OFTC, thanks to everyone
who have helped testing the patches and submitted UI suggestions.

src/otr/Makefile.am

@@ -0,0 +1,42 @@
+moduledir = $(libdir)/irssi/modules
+
+module_LTLIBRARIES = $(otr_module_lib)
+noinst_LTLIBRARIES = $(otr_static_lib)
+
+EXTRA_LTLIBRARIES = \
+	libotr_core.la \
+	libotr_core_static.la
+
+AM_CPPFLAGS = \
+	-I$(top_srcdir)/src \
+	-I$(top_srcdir)/src/core/ \
+	-I$(top_srcdir)/src/irc/core/ \
+	-I$(top_srcdir)/src/fe-common/core/ \
+	-I$(top_srcdir)/src/fe-text/ \
+	$(GLIB_CFLAGS) \
+	$(OTR_CFLAGS)
+
+libotr_core_la_LDFLAGS = -module -avoid-version -rpath $(moduledir)
+libotr_core_la_LIBADD = $(OTR_LDFLAGS)
+
+otr_sources = \
+	key.c \
+	module.c \
+	otr-formats.c \
+	otr-ops.c \
+	otr-fe.c \
+	otr.c
+
+libotr_core_la_SOURCES = \
+	$(otr_sources)
+
+libotr_core_static_la_SOURCES = \
+	$(otr_sources)
+
+noinst_HEADERS = \
+	irssi-otr.h \
+	key.h \
+	module.h \
+	otr-formats.h \
+	otr-fe.h \
+	otr.h