Add saving of 24 and 32-bit images to BMP format.

core/image/bmp/bmp_os.odin

@@ -2,6 +2,7 @@
 package core_image_bmp
 
 import "core:os"
+import "core:bytes"
 
 load :: proc{load_from_file, load_from_bytes, load_from_context}
 
@@ -16,4 +17,18 @@ load_from_file :: proc(filename: string, options := Options{}, allocator := cont
 	} else {
 		return nil, .Unable_To_Read_File
 	}
+}
+
+save :: proc{save_to_buffer, save_to_file}
+
+save_to_file :: proc(output: string, img: ^Image, options := Options{}, allocator := context.allocator) -> (err: Error) {
+	context.allocator = allocator
+
+	out := &bytes.Buffer{}
+	defer bytes.buffer_destroy(out)
+
+	save_to_buffer(out, img, options) or_return
+	write_ok := os.write_entire_file(output, out.buf[:])
+
+	return nil if write_ok else .Unable_To_Write_File
 }