[FL-1906] Documentation: add Doxyfile, prepare sources for doxygen. (#741)

* Documentation: add Doxyfile, prepare sources for doxygen.

* Update ReadMe and remove obsolete CLA

* Add contribution guide

* Contributing: update text

* Correct spelling

core/furi/memmgr.h

@@ -1,3 +1,8 @@
+/**
+ * @file memmgr.h
+ * Furi: memory managment API and glue
+ */
+
 #pragma once
 
 #include <stddef.h>
@@ -12,14 +17,27 @@ extern "C" {
 // define for test case "link against furi memmgr"
 #define FURI_MEMMGR_GUARD 1
 
+/** Get free heap size
+ *
+ * @return     free heap size in bytes
+ */
 size_t memmgr_get_free_heap(void);
+
+/** Get heap watermark
+ *
+ * @return     minimum heap in bytes
+ */
 size_t memmgr_get_minimum_free_heap(void);
 
-inline static void* furi_alloc(size_t size) {
-    void* p = malloc(size);
-    furi_check(p);
-    return memset(p, 0, size);
-}
+/** Allocate memory from heap
+ *
+ * @note       performs memset with 0, will crash system if not enough memory
+ *
+ * @param[in]  size  bytes to allocate
+ *
+ * @return     pointer to allocated memory
+ */
+void* furi_alloc(size_t size);
 
 #ifdef __cplusplus
 }