Add some easy way to install

I know that this should be done using some sort of build system (like meson), but the player is still far from finished and a basic install script should be sufficient for the time being, if anyone wishes to test it.

install.sh

@@ -0,0 +1,37 @@
+#!/bin/sh
+
+LICENSES_DIR="/usr/local/share/licenses/clapper"
+DOC_DIR="/usr/local/share/doc/clapper"
+MAIN_DIR="/usr/local/share/clapper"
+BIN_DIR="/usr/local/bin"
+GJS_DIR="/usr/local/share/gjs-1.0"
+
+SCRIPT_ERR="Error: this script must be"
+
+if [ ! -d "./clapper_src" ]; then
+    echo "$SCRIPT_ERR run from clapper directory!" 1>&2
+    exit 1
+elif [ "$EUID" -ne 0 ]; then
+    echo "$SCRIPT_ERR run as root!" 1>&2
+    exit 1
+fi
+
+echo "Creating directories..."
+mkdir -p "$LICENSES_DIR"
+mkdir -p "$DOC_DIR"
+mkdir -p "$MAIN_DIR"
+mkdir -p "$GJS_DIR"
+mkdir -p "$BIN_DIR"
+
+echo "Copying files..."
+cp -f "./COPYING" "$LICENSES_DIR/"
+cp -f "./README.md" "$DOC_DIR/"
+cp -rf "./clapper_src" "$MAIN_DIR/"
+cp -f "./main.js" "$MAIN_DIR/"
+cp -f "./gjs-1.0/clapper.js" "$GJS_DIR/"
+cp -f "./bin/clapper" "$BIN_DIR/"
+
+echo "Creating executables..."
+chmod +x "$BIN_DIR/clapper"
+
+echo "Install finished"