set title based on prefix and suffix (#23)

Co-authored-by: Guilherme Rugai Freire <41879254+GRFreire@users.noreply.github.com>
Co-authored-by: NRK <nrk@disroot.org>
Co-authored-by: Berke Kocaoğlu <berke.kocaoglu@metu.edu.tr>

config.def.h

@@ -12,6 +12,21 @@ enum {
  */
 
 #endif
+
+#ifdef _TITLE_CONFIG
+
+/* default title prefix */
+static const char *TITLE_PREFIX = "sxiv - ";
+
+/* default title suffixmode, available options are:
+ * SUFFIX_EMPTY
+ * SUFFIX_BASENAME
+ * SUFFIX_FULLPATH
+ */
+static const suffixmode_t TITLE_SUFFIXMODE = SUFFIX_BASENAME;
+
+#endif
+
 #ifdef _IMAGE_CONFIG
 
 /* levels (in percent) to use when zooming via '-' and '+':