Re-organize the shells' initialization logic

- unify ~/.config/shell/aliases.sh and ~/.config/shell/utils.sh
  into a common ~/.config/shell/init.sh
- split the contents of ~/.config/shell/aliases.sh
  into the folder ~/.config/shell/aliases.d
- split the contents of ~/.config/shell/utils.sh
  into the folder ~/.config/shell/utils.d

.config/shell/utils.d/web.sh

@@ -0,0 +1,26 @@
+# This file defines various utilities regarding "the web"
+
+
+_command_exists() {
+    command -v "$1" 1>/dev/null 2>&1
+}
+
+
+# List all internal IPs
+internal-ips() {
+    if _command_exists ifconfig; then
+        ifconfig | awk '/inet /{ gsub(/addr:/, ""); print $2 }'
+    else
+        echo 'ifconfig not installed'
+    fi
+}
+
+
+# Obtain a weather report
+weather() {
+    if [ -n "$1" ]; then
+        curl "v1.wttr.in/$1"
+    else
+        curl 'v1.wttr.in'
+    fi
+}