Fix #117: add :version command

:version currently fills the command line with the version number in
order to display it to the user (hacky) and copies it to the clipboard.

scripts/build.sh

@@ -10,6 +10,6 @@ scripts/excmds_macros.py
 scripts/newtab.md.sh
 scripts/make_docs.sh &
 
-webpack --display errors-only &
+(webpack --display errors-only && scripts/git_version.sh)&
 
 wait

scripts/git_version.sh

@@ -0,0 +1,5 @@
+#!/usr/bin/env bash
+
+version=$(git describe --tags)
+
+sed -i 's/REPLACE_ME_WITH_THE_VERSION_USING_SED/'$version'/' ./build/background.js

src/excmds.ts

@@ -511,6 +511,13 @@ export function suppress(preventDefault?: boolean, stopPropagation?: boolean) {
     mode("ignore")
 }
 
+//#background
+export function version(){
+    clipboard("yank","REPLACE_ME_WITH_THE_VERSION_USING_SED")
+    fillcmdline_notrail("REPLACE_ME_WITH_THE_VERSION_USING_SED")
+
+}
+
 /** Example:
         - `mode ignore` to ignore all keys.
 */