added projects plugin and completion

plugins/available/projects.plugin.bash

@@ -0,0 +1,31 @@
+cite about-plugin
+about-plugin 'add "export PROJECT_PATHS=~/projects:~/intertrode/projects" to navigate quickly to your project directories with `pj` and `pjo`'
+
+function pj {
+    about 'navigate quickly to your various project directories'
+    group 'projects'
+
+    if [ -n "$PROJECT_PATHS" ]; then
+        local cmd
+
+        if [ "$1" == "open" ]; then
+            shift
+            cmd="$EDITOR"
+        fi
+
+        cmd="${cmd:-cd}"
+
+        if [ -n "$1" ]; then
+            for i in ${PROJECT_PATHS//:/$'\n'}; do
+                if [ -d "$i"/"$1" ]; then
+                    $cmd "$i"/"$1"
+                    return
+                fi
+            done
+        fi
+    fi
+
+    echo "No such project '$1'"
+}
+
+alias pjo="pj open"