advotracker_client: introduce Windows icon handling

* include `windres` crate
* create a `build.rs`
* include a `hotline.svg` that is converted to advotracker.ico
  using inkscape and imagemagick
* crate a `README.md`

Signed-off-by: Ralf Zerres <ralf.zerres@networkx.de>

crates/advotracker_client/build.rs

@@ -0,0 +1,19 @@
+/*
+ * advotracker - Hotline tackingtool for Advocats
+ *
+ * Copyright 2021 Ralf Zerres <ralf.zerres@networkx.de>
+ * SPDX-License-Identifier: (0BSD or MIT)
+ */
+
+use winres;
+
+fn main() {
+    if cfg!(target_os = "windows") {
+        let mut res = winres::WindowsResource::new();
+        res.set_icon("assets/icons/adovtracker/advotracker.ico")
+            .set("InternalName", "ADVOTRACKER.EXE")
+        // manually set version 0.1.5.2
+            .set_version_info(winres::VersionInfo::PRODUCTVERSION, 0x0000000100050002);
+        res.compile().unwrap();
+    }
+}