post release announcement (1.5.1) cleanup of RELEASE_NOTES

RELEASE_NOTES

@@ -11,34 +11,6 @@ is making sure that spelling/grammer/whatever is usable and that you are using
 The release team should empty this file after each release.
 
 
-There is a new experimental function to gray out not available languages in the
-language selection dialog. This feature is available when Wesnoth is started
-with the --new-widgets parameter. Packagers of various platforms are encouraged
-to test this feature and report bugs when found. 
 
-Users of Wesnoth 1.5.0 are encouraged to upgrade since Wesnoth 1.5.0 won't be
-compatible with recent changes to the addon server.
 
-"Host Network Game" feature in multiplayer menu requires "wesnothd" server to 
-be compiled. Wesnothd is looked for by default in the same directory wesnoth was 
-launched from. This can be changed in userdata/preferences by setting 
-wesnothd_name="/path/to/wesnothd". Windows version is 
-wesnothd_name="C:\path\to\wesnothd.exe"
 
-Now content authors can specify the type of their addons. See the documentation
-updates at http://www.wesnoth.org/wiki/PblWML for details.
-
-Multiplayer era authors can put their [binary_path] declarations inside the
-MULTIPLAYER #ifdef block (or similar). This was a fix to an ancient, forgotten
-bug that a developer noticed while playing a single-player campaign that
-conflicted with a multiplayer era's binary_path.
-
-The confusion caused by name and wiki entry regarding [attacks] special has been
-sorted out. What was [attacks] up till now was now logicaly renamed [swarm] and
-a completely new [attacks] has been created behaving alike to [damage] and 
-[chance_to_hit]. If an attack uses [swarm] any [attacks] declared will be
-ignored.
-
-WML authors can now choose if they want [event] spawned inside an [event] to have
-variables evaluated immediately (new behavior) or at execution time (1.4 one, default) by
-using a delayed_variable_substitution= key. Defaults to yes.