Change default download location

`/url save $someurl` will now download to
`~/.local/share/profanity/downloads/from_jid/date/filename` instead of
`~/.local/share/profanity/downloads`.

Like this the downloaded files should be better ordered.

This will only happen for MUC and 1:1 chat windows.
Private windows might have only a nick or jid. Lets not distinguish
between those two ways. And since the nick option is unreliable to be
the same person lets just put them in the general downloads folder.
As is done with downloads from all other windows as well.

I also had the idea to make this configurable but this suits my needs
and time limits right now.

src/config/files.c

@@ -164,6 +164,22 @@ files_get_data_path(const char* const location)
     return g_strdup_printf("%s/profanity/%s", xdg_data, location);
 }
 
+gchar*
+files_get_download_path(const char* const jid)
+{
+    auto_gchar gchar* xdg_data = _files_get_xdg_data_home();
+
+    if (jid) {
+        auto_char char* account_dir = str_replace(jid, "@", "_at_");
+        GDateTime* now = g_date_time_new_now_local();
+        auto_gchar gchar* date = g_date_time_format(now, "%Y_%m_%d");
+        g_date_time_unref(now);
+        return g_strdup_printf("%s/profanity/%s/%s/%s", xdg_data, DIR_DOWNLOADS, account_dir, date);
+    } else {
+        return g_strdup_printf("%s/profanity/%s", xdg_data, DIR_DOWNLOADS);
+    }
+}
+
 gchar*
 files_get_account_data_path(const char* const specific_dir, const char* const jid)
 {

src/config/files.h

@@ -66,6 +66,7 @@ void files_create_directories(void);
 
 gchar* files_get_config_path(const char* const config_base);
 gchar* files_get_data_path(const char* const location);
+gchar* files_get_download_path(const char* const jid);
 gchar* files_get_account_data_path(const char* const specific_dir, const char* const jid);
 
 gchar* files_get_log_file(const char* const log_file);