Add support for versioning

When building znc-push with the makefile, it will modify the
PUSHVERSION define with version info from `git describe`, build the
module, and then reset PUSHVERSION back to "dev".  When building
directly from znc-buildmod, this will ensure the version is always just
"dev".

A matching command -- `version` -- has been added to the module which
will simply echo the value of PUSHVERSION at the time of compilation.

Makefile

@@ -1,5 +1,9 @@
+version := $(shell git describe)
+
 push.so: push.cpp
+	sed -i -e "s|PUSHVERSION \".*\"|PUSHVERSION \"$(version)\"|" push.cpp
 	znc-buildmod push.cpp
+	sed -i -e "s|PUSHVERSION \".*\"|PUSHVERSION \"dev\"|" push.cpp
 
 install: push.so
 	cp push.so $(HOME)/.znc/modules/push.so

README.md

@@ -99,6 +99,10 @@ Commands
 
     Links you to this fine document.
 
+*   `version`
+
+    Tells you the tagged build version currently running.
+
 *   `set <option> <value>`
 
     Allows you to modify configuration values.

push.cpp

@@ -9,6 +9,7 @@
  */
 
 #define REQUIRESSL
+#define PUSHVERSION "dev"
 
 #include <znc/znc.h>
 #include <znc/Chan.h>
@@ -1425,6 +1426,11 @@ class CPushMod : public CModule
 			{
 				PutModule("View the detailed documentation at https://github.com/jreese/znc-push/blob/master/README.md");
 			}
+			// VERSION command
+			else if (action == "version")
+			{
+				PutModule("znc-push " + CString(PUSHVERSION));
+			}
 			// EVAL command
 			else if (action == "eval")
 			{