DOCS/client_api_examples: move all examples into their own subdirs

Also get rid of shared.h; it actually doesn't have much value. Just copy
the tiny function it contained into the 2 files which used it.

DOCS/client_api_examples/simple/simple.c

@@ -0,0 +1,52 @@
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "libmpv/client.h"
+
+static inline void check_error(int status)
+{
+    if (status < 0) {
+        printf("mpv API error: %s\n", mpv_error_string(status));
+        exit(1);
+    }
+}
+
+int main(int argc, char *argv[])
+{
+    if (argc != 2) {
+        printf("pass a single media file as argument\n");
+        return 1;
+    }
+
+    mpv_handle *ctx = mpv_create();
+    if (!ctx) {
+        printf("failed creating context\n");
+        return 1;
+    }
+
+    // Enable default key bindings, so the user can actually interact with
+    // the player (and e.g. close the window).
+    check_error(mpv_set_option_string(ctx, "input-default-bindings", "yes"));
+    mpv_set_option_string(ctx, "input-x11-keyboard", "yes");
+    int val = 1;
+    check_error(mpv_set_option(ctx, "osc", MPV_FORMAT_FLAG, &val));
+
+    // Done setting up options.
+    check_error(mpv_initialize(ctx));
+
+    // Play this file.
+    const char *cmd[] = {"loadfile", argv[1], NULL};
+    check_error(mpv_command(ctx, cmd));
+
+    // Let it play, and wait until the user quits.
+    while (1) {
+        mpv_event *event = mpv_wait_event(ctx, 10000);
+        printf("event: %s\n", mpv_event_name(event->event_id));
+        if (event->event_id == MPV_EVENT_SHUTDOWN)
+            break;
+    }
+
+    mpv_terminate_destroy(ctx);
+    return 0;
+}