refactor: remove dc prefix from keyring and keyhistory

src/keyhistory.rs

@@ -0,0 +1,14 @@
+use crate::context::Context;
+use crate::types::*;
+
+/* yes: uppercase */
+/* library private: key-history */
+pub fn dc_add_to_keyhistory(
+    _context: &Context,
+    _rfc724_mid: *const libc::c_char,
+    _sending_time: time_t,
+    _addr: *const libc::c_char,
+    _fingerprint: *const libc::c_char,
+) {
+
+}