Properly add QtQuickWidgets dependency

README.asciidoc

@@ -100,6 +100,7 @@ The following software and libraries are required to run qutebrowser:
 * http://qt.io/[Qt] 5.7.1 or newer (5.10 recommended) with the following modules:
   - QtCore / qtbase
   - QtQuick (part of qtbase in some distributions)
+  - QtQuickWidgets (part of qtbase/QtQuick in some distributions)
   - QtSQL (part of qtbase in some distributions)
   - QtOpenGL
   - QtWebEngine, or

doc/changelog.asciidoc

@@ -55,6 +55,10 @@ Added
 Changed
 ~~~~~~~
 
+- New dependency on the `PyQt5.QtQuickWidgets` module (which was already
+  accidentally introduced in v1.3.2). For most distributions, this is already
+  contained in the existing dependencies - only distributions which have
+  separate packages for PyQt submodules might be affected.
 - The Windows/macOS releases now bundle Qt 5.11.1 which is based on
   Chromium 65.0.3325.151 with security fixes up to Chromium 67.0.3396.87.
 - New short flags for commandline arguments: `-B` and `-T` for `--basedir` and

qutebrowser/misc/earlyinit.py

@@ -233,6 +233,7 @@ def check_libraries():
         'PyQt5.QtQml': _missing_str("PyQt5.QtQml"),
         'PyQt5.QtSql': _missing_str("PyQt5.QtSql"),
         'PyQt5.QtOpenGL': _missing_str("PyQt5.QtOpenGL"),
+        'PyQt5.QtQuickWidgets': _missing_str("PyQt5.QtQuickWidgets"),
     }
     _check_modules(modules)