Thanks @Zeno-

This was needed due to the TileDef serialisation changes. Originally it has been planned
to also add utf-8 based chat to 26, but chat changes aren't final yet, so they are done
in one change, after the release, and not two small ones, causing us having to be compliant
to three versions of the packet.

Enable the server to request the client to reconnect.

This can be done with the now extended minetest.request_shutdown([reason], [reconnect]) setting.

-> Fix server crash with protocol >=25 if a default password is set.
-> Remove some useless and possibly confusion causing code for the TOCLIENT_FIRST_SRP packet handler

Improve TOCLIENT_ACTIVE_OBJECT_MESSAGES robustness for handling invalid data

Use wide_to_utf8 and utf8_to_wide instead of wide_to_narrow and narrow_to_wide at almost all places.
Only exceptions: test functions for narrow conversion, and chat, which is done in a separate commit.

Previously, m_proto_ver was set to the serialisation version
inside the legacy init packet.

Now, if the server doesn't send a protocol version (protocols < 25),
we set m_proto_ver to some value < 25 and > 0.

Fix grammar error and missing number conversion for version.
Also add deployed protocol to log line.

* Use enum for GENERIC_CMD_*
* Rename m_attachements to attachement_parent_ids (public member and clearer name)
* Rename GENERIC_CMD_SET_ATTACHMENT to GENERIC_CMD_ATTACH_TO
* USHRT_MAX + 1 buffer sizes to prevent overflows as @kahrl suggested
* Remove unneccessary m_id from GenericCAO (shadowing protected superclass member for no reason) as @kahrl suggested

Thanks to @UltimateNate for pointing this out :)

Also, clean up surrounding code style
Replace by-value parameter passing with const refs when possible
Fix post-increment of iterators

Its a possible mistake to log in to a server with twice the same name.
Before, it triggered a server wide error message, now it logs to actionstream.

Also rename method to better match what it does.

This enables srp.

Adds everything needed for SRP (and everything works too),
but still deactivated, as protocol v25 init packets aren't final yet.
Can be activated by changing the LATEST_PROTOCOL_VERSION header to 25
inside networkprotocol.h.

Also fix std::logic_error when server::DenyAccess() is used with only two arguments.

Change types for passed password from wstring to string, which removes converting
back and forth in most cases. Move the narrow_to_wide conversion, where its neccessary,
closer to irrlicht. Remove trailing spaces in guiPasswordChange.cpp. Make parameters for
translatePassword passed as const reference.

Also set the packet size at creation not when pushing rawString, no functional change

This seems to be a debug message which has been forgotten to be removed.

Create PacketError exception and use it with ACTIVEOBJECT_REMOVE_ADD handler which can be unreliable

Move debug streams to log.cpp|h

Move GUI-related globals to clientlauncher

Move g_settings and g_settings_path to settings.cpp|h

Move g_menuclouds to clouds.cpp|h

Move g_profiler to profiler.cpp|h

Use a common function to check the reading offset

Because we get a Buffer<u8> from ConnectionEvent, don't convert it to SharedBuffer<u8> and return it to Server/Client::Receive which will convert it to NetworkPacket
Instead, put the Buffer<u8> directly to NetworkPacket and return it to packet processing
This remove a long existing memory copy
Also check the packet size directly into Connection::Receive instead of packet processing

remove command from queue on success, else do nothing, instead of remove command from queue and push it front on success

This removes a lot of narrow/wide conversions where a wide string was never used.

  * Combine client and server man pages.
  * Update unit test options and available databases in man page.
  * Add `--worldname` to man page.
  * Fix a bunch of places where `"Minetest"` was used directly instead of `PROJECT_NAME`.
  * Disable server build by default on all operating systems.
  * Make `ENABLE_FREETYPE` not fail if FreeType isn't found.
  * Enable LevelDB, Redis, and FreeType detection by default.
  * Remove the `VERSION_PATCH_ORIG` hack.
  * Add option to search for and use system JSONCPP.
  * Remove broken LuaJIT version detection.
  * Rename `DISABLE_LUAJIT` to `ENABLE_LUAJIT`.
  * Rename `minetest_*` variables in `version.{h,cpp}` to `g_*`.
  * Clean up style of CMake files.