[gtksourceview] build: GTK+ >= 3.15.0 is required

[Sébastien Wilmet <swilmet src gnome org>]

commit 014d0e7d8410fbaaad1e15717346622dca0a8922
Author: Sébastien Wilmet <swilmet gnome org>
Date:   Sun Nov 2 17:21:21 2014 +0100

    build: GTK+ >= 3.15.0 is required
    
    Because the GtkTextView:monospace property is used.

 README       |    2 +-
 configure.ac |    2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)
---
diff --git a/README b/README
index 7821975..9223d2d 100644
--- a/README
+++ b/README
@@ -29,7 +29,7 @@ the GNU Lesser General Public License.
 Installation
 ============
 
-GtkSourceView requires GLib >= 2.38, GTK+ >= 3.14 and libxml2 >= 2.6.
+GtkSourceView requires GLib >= 2.38, GTK+ >= 3.15.0 and libxml2 >= 2.6.
 
 Simple install procedure:
 
diff --git a/configure.ac b/configure.ac
index 8b81bb2..2f38215 100644
--- a/configure.ac
+++ b/configure.ac
@@ -58,7 +58,7 @@ AC_CHECK_HEADERS([unistd.h])
 
 # Dependencies
 GLIB_REQUIRED_VERSION=2.38
-GTK_REQUIRED_VERSION=3.13.7
+GTK_REQUIRED_VERSION=3.15.0
 LIBXML_REQUIRED_VERSION=2.6.0
 GLADE_UI_REQUIRED=3.9