feat(cli): add convert option to generate html presentations (#66)

* wip(cli): convert slides to html using RevealJS

* wip: convert - almost fully working

* [pre-commit.ci] auto fixes from pre-commit.com hooks

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* fix: remove unused file

* fix: add last slides in now performed during rendering

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* chore(ci): testing ConvertExample too

* fix: ManimGL does not consider wait as an animation

* [pre-commit.ci] auto fixes from pre-commit.com hooks

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Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

manim_slides/slide.py

@@ -14,8 +14,15 @@ from .manim import FFMPEG_BIN, MANIMGL, Scene, ThreeDScene, config, logger
 def reverse_video_file(src: str, dst: str) -> None:
     """Reverses a video file, writting the result to `dst`."""
     command = [FFMPEG_BIN, "-i", src, "-vf", "reverse", dst]
+    logger.debug(" ".join(command))
     process = subprocess.Popen(command, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
-    process.communicate()
+    output, error = process.communicate()
+
+    if output:
+        logger.debug(output.decode())
+
+    if error:
+        logger.debug(error.decode())
 
 
 class Slide(Scene):
@@ -96,6 +103,17 @@ class Slide(Scene):
         self.current_slide += 1
         self.pause_start_animation = self.current_animation
 
+    def add_last_slide(self) -> None:
+        """Adds a 'last' slide to the end of slides."""
+        self.slides.append(
+            SlideConfig(
+                type=SlideType.last,
+                start_animation=self.pause_start_animation,
+                end_animation=self.current_animation,
+                number=self.current_slide,
+            )
+        )
+
     def start_loop(self) -> None:
         """Starts a loop."""
         assert self.loop_start_animation is None, "You cannot nest loops"
@@ -124,6 +142,8 @@ class Slide(Scene):
 
         Note that cached files only work with Manim.
         """
+        self.add_last_slide()
+
         if not os.path.exists(self.output_folder):
             os.mkdir(self.output_folder)