adjusting settings and slide_model.rs

These are trying to get more code written in Rust rather than c++. Not
there yet, but I need to sync these to another machine.

build.sh

@@ -1,5 +1,30 @@
 #!/bin/sh
 
-cmake -B bld/ .
-make -j8 --dir bld/
-rm -rf ~/.cache/librepresenter/Libre\ Presenter/qmlcache/
+function build_debug () {
+    cmake -B bld/ .
+    make -j8 --dir bld/
+    rm -rf ~/.cache/librepresenter/Libre\ Presenter/qmlcache/
+}
+
+function build_release () {
+    cmake -DCMAKE_BUILD_TYPE=Release -B bld/ .
+    make -j8 --dir bld/
+    rm -rf ~/.cache/librepresenter/Libre\ Presenter/qmlcache/
+}
+
+while [[ $# -gt 0 ]]; do
+    case $1 in
+        -d|--debug)
+            build_debug
+            shift # past value
+            ;;
+        -r|--release)
+            build_release
+            shift # past value
+            ;;
+        *)
+            POSITIONAL_ARGS+=("$1") # save positional arg
+            shift # past argument
+            ;;
+    esac
+done