UART write example (#53)

* Rename test functions

* rewrite furi API, segfault

* make fixes in FURI, log through FURI

* add uart write example blank

* implement fuprintf instead of fopencookie

* add gif, blank page

* UART write example description

Co-authored-by: Vadim Kaushan <admin@disasm.info>

core/log.c

@@ -0,0 +1,25 @@
+#define _GNU_SOURCE
+
+#include <stdio.h>
+#include <stdarg.h>
+#include <string.h>
+
+#include "log.h"
+#include "furi.h"
+
+#define PRINT_STR_SIZE 64
+
+void fuprintf(FuriRecordSubscriber* f, const char * format, ...) {
+    char buffer[PRINT_STR_SIZE];
+
+    va_list args;
+    va_start(args, format);
+    vsprintf(buffer, format, args);
+    va_end(args);
+
+    furi_write(f, buffer, strlen(buffer));
+}
+
+FuriRecordSubscriber* get_default_log() {
+    return furi_open("tty", false, false, NULL, NULL);
+}