Fix Windows build

LICENSE

@@ -1,6 +1,6 @@
 BSD 2-Clause License
 
-Copyright (c) 2021, Vasiliy Tereshkov
+Copyright (c) 2021-2023, Vasiliy Tereshkov
 All rights reserved.
 
 Redistribution and use in source and binary forms, with or without

RAYLIB_LICENSE

@@ -0,0 +1,16 @@
+Copyright (c) 2013-2023 Ramon Santamaria (@raysan5)
+
+This software is provided "as-is", without any express or implied warranty. In no event 
+will the authors be held liable for any damages arising from the use of this software.
+
+Permission is granted to anyone to use this software for any purpose, including commercial 
+applications, and to alter it and redistribute it freely, subject to the following restrictions:
+
+  1. The origin of this software must not be misrepresented; you must not claim that you 
+  wrote the original software. If you use this software in a product, an acknowledgment 
+  in the product documentation would be appreciated but is not required.
+
+  2. Altered source versions must be plainly marked as such, and must not be misrepresented
+  as being the original software.
+
+  3. This notice may not be removed or altered from any source distribution.

build_umplot_windows_mingw.bat

@@ -1 +1 @@
-gcc -O3 umplot.c -o umplot.umi -shared -Wl,--dll -static-libgcc -static -lraylib -lumka -L%cd% -lkernel32 -luser32 -lgdi32 -lwinmm 
+gcc -O3 -DUMKA_STATIC umplot.c -o umplot_windows.umi -shared -Wl,--dll -static-libgcc -static -lumka_static -lraylib -L. -lkernel32 -luser32 -lgdi32 -lwinmm 

umplot.c

@@ -7,6 +7,13 @@
 #include "font.h"
 
 
+#ifdef _WIN32
+    #define UMPLOT_API __declspec(dllexport)
+#else
+    #define UMPLOT_API __attribute__((visibility("default")))
+#endif
+
+
 enum
 {
     STYLE_LINE = 1,
@@ -424,7 +431,7 @@ static void drawZoomRect(Rectangle zoomRect, const ScreenTransform *transform)
 }
 
 
-void umplot_plot(UmkaStackSlot *params, UmkaStackSlot *result)
+UMPLOT_API void umplot_plot(UmkaStackSlot *params, UmkaStackSlot *result)
 {
     Plot *plot = (Plot *) params[0].ptrVal;
 

umplot.um

@@ -51,9 +51,6 @@ fn (s: ^Series) clear*() {
 }
 
 fn (s: ^Series) add*(x, y: real) {
-    if !valid(s.points) {
-        s.clear()
-    }
     s.points = append(s.points, Point{x, y})
 }
 

umplottest.um

@@ -4,7 +4,7 @@ fn main() {
     plt := umplot.init(4)
 
     for i := 0; i < 4; i++ {
-        plt.series[i].name = "Sine wave " + repr(i + 1)
+        plt.series[i].name = sprintf("Sine wave %d", i + 1)
 
         for x := 0.0; x <= 100.0; x += 1.0 {
             y := (1 + 0.5 * i) * sin(x / 10.0 + i)