Enable live-reloading of the config

 - Allow reloading config.txt by pressing 'R' while the program is
   running.

 - Update the README to add more information.

 - Call IncreaseIterations once to keep the window from starting out
   blank.

README.md

@@ -1,7 +1,45 @@
 3D L-System Viewer
 ==================
 
-I will write a README when the project is done.
+This is a small OpenGL program that renders uses an L-system and turtle
+graphics to draw 3D fractals.
+
+
+Compiling
+=========
+
+Building this requires `gcc` to be installed and available on your path, and
+for the GLFW to be installed.
+
+On Linux
+--------
+
+Edit the `Makefile` to replace the `GLFW_DIR` variable with the path where GLFW
+is installed on your system. Alternatively, set the `GLFW_DIR` environment
+variable. Afterwards run `make` to compile the program.
+
+On Windows
+----------
+
+Edit `build_windows.bat` and replace any occurrences of `C:\bin\glfw-3.3.3\`
+with the path where GLFW is installed on your system. Afterwards, run
+`build_windows.bat` to compile the program.
+
+
+Running the Program
+===================
+
+Run `./l_system_3d` (or `l_system_3d.exe` on Windows). A window should appear
+displaying an L-system rendering. This can be controlled using some simple
+keypresses:
+
+ - Increase iterations by 1: Press the "up" arrow key.
+
+ - Decrease iterations by 1: Press the "down" arrow key.
+
+ - Reload the config file: Press the "R" key.
+
+ - Quit the program: Close the window, or press the escape key.
 
 Configuring the L-System
 ========================
@@ -14,7 +52,9 @@ encountering each character. (The `actions` line must occur exactly once in the
 config.)
 
 If you want a longer example, the default "config.txt" contains instructions
-for drawing the dragon curve, and is shown below:
+for drawing a pair of connected dragon curves. A simpler, single, dragon-curve
+example can be obtained by replacing the contents of "config.txt" with the
+following lines:
 ```
 init F
 F F+G

l_system_3d.c

@@ -201,6 +201,22 @@ static int DecreaseIterations(ApplicationState *s) {
   return 1;
 }
 
+// Reloads the config file from ./config.txt. If this fails, then we'll just
+// print a message and return. (The config can be faulty at runtime, but we
+// won't start the program unless it's OK.)
+static void ReloadConfig(ApplicationState *s) {
+  LSystemConfig *new_config = NULL;
+  LSystemConfig *old_config = s->config;
+  new_config = LoadLSystemConfig("./config.txt");
+  if (!new_config) {
+    printf("Failed loading new config file.\n");
+    return;
+  }
+  s->config = new_config;
+  DestroyLSystemConfig(old_config);
+  printf("Config updated OK.\n");
+}
+
 static int ProcessInputs(ApplicationState *s) {
   int pressed;
   if (glfwGetKey(s->window, GLFW_KEY_ESCAPE) == GLFW_PRESS) {
@@ -229,6 +245,16 @@ static int ProcessInputs(ApplicationState *s) {
     // Down pressed -> down released
     s->key_pressed_tmp = 0;
   }
+  pressed = glfwGetKey(s->window, GLFW_KEY_R) == GLFW_PRESS;
+  if (!s->key_pressed_tmp && pressed) {
+    // Nothing pressed -> R pressed
+    s->key_pressed_tmp = GLFW_KEY_R;
+    ReloadConfig(s);
+    if (!GenerateVertices(s)) return 0;
+  } else if ((s->key_pressed_tmp == GLFW_KEY_R) && !pressed) {
+    // R pressed -> R released
+    s->key_pressed_tmp = 0;
+  }
   return 1;
 }
 
@@ -338,7 +364,11 @@ int main(int argc, char **argv) {
     to_return = 1;
     goto cleanup;
   }
-  // TODO: Display a test model if the config is faulty.
+  if (!IncreaseIterations(s)) {
+    printf("Error running first L-system iteration.\n");
+    to_return = 1;
+    goto cleanup;
+  }
   if (!GenerateVertices(s)) {
     printf("Failed generating vertices.\n");
     to_return = 1;