Finish implementing the /web/xxx methods

[ryanc-me]

• /web/session/get_lang_list (only v15+?)
• /web/session/check
• /web/session/change_password
• /web/session/get_session_info
• /web/session/modules
• /web/session/modules
• /web/session/destroy
• /web/session/logout
• /web/dataset/resequence
• /web/dataset/call
• /web/dataset/call_kw
• /web/dataset/load
• /web/dataset/search_read