refactor chat history to allow scrolling

src/misc_tools.h

@@ -67,7 +67,7 @@ int qsort_strcasecmp_hlpr(const void *nick1, const void *nick2);
       - cannot be empty
       - cannot start with a space
       - must not contain contiguous spaces */
-bool valid_nick(uint8_t *nick);
+int valid_nick(uint8_t *nick);
 
 /* Moves the cursor to the end of the line in given window */
 void mv_curs_end(WINDOW *w, size_t len, int max_y, int max_x);