[mutter] Bump version to 3.15.91

[Florian Müllner <fmuellner src gnome org>]

commit 18f958d06d2a7ef9acdbbdbfa67b23470b275967
Author: Florian Müllner <fmuellner gnome org>
Date:   Wed Mar 4 19:41:07 2015 +0100

    Bump version to 3.15.91
    
    Update NEWS.

 NEWS         |   19 +++++++++++++++++++
 configure.ac |    2 +-
 2 files changed, 20 insertions(+), 1 deletions(-)
---
diff --git a/NEWS b/NEWS
index 093df9f..6c0cc11 100644
--- a/NEWS
+++ b/NEWS
@@ -1,3 +1,22 @@
+3.15.91
+=======
+* wayland: Fix nested compositor mode [Jonas; #745401]
+* wayland: Fix pointer constraining [Marek; #727337]
+* wayland: Fix input region on HiDPI [Jonas; #744933]
+* Allow themes to style buttons differently based on function [Horst; #745108]
+* Misc. bug fixes and cleanups [Ray, Rui, Alban; #745141, #745118, #745476,
+  #745442]
+
+Contributors:
+  Jonas Ådahl, Alban Browaeys, Marek Chalupa, Horst, Rui Matos,
+  Jasper St. Pierre, Ray Strode
+
+Translations:
+  Chao-Hsiung Liao [zh_TW], Efstathios Iosifidis [el], Dušan Kazik [sk],
+  Balázs Úr [hu], Daniel Mustieles [es], Claude Paroz [fr], Stas Solovey [ru],
+  Yosef Or Boczko [he], Rafael Ferreira [pt_BR], Aurimas Černius [lt],
+  Fran Dieguez [gl], Anders Jonsson [sv], Мирослав Николић [sr, sr latin]
+
 3.15.90
 =======
 * Initialize MetaOutput even when we can't get the EDID [Rui; #743412]
diff --git a/configure.ac b/configure.ac
index 71394e1..e625ee5 100644
--- a/configure.ac
+++ b/configure.ac
@@ -2,7 +2,7 @@ AC_PREREQ(2.62)
 
 m4_define([mutter_major_version], [3])
 m4_define([mutter_minor_version], [15])
-m4_define([mutter_micro_version], [90])
+m4_define([mutter_micro_version], [91])
 
 m4_define([mutter_version],
           [mutter_major_version.mutter_minor_version.mutter_micro_version])