improve file selection button, first version of uw8-tool to build base.wasm

uw8-tool/src/main.rs

@@ -0,0 +1,9 @@
+mod base_module;
+
+use base_module::BaseModule;
+use anyhow::Result;
+
+fn main() -> Result<()> {
+    BaseModule::for_format_version(1)?.write_to_file("base.wasm")?;
+    Ok(())
+}