CMFileManager: Themes support + Dark theme

This change enabled the theme support, and added a new dark theme under the package
CMFileManagerThemes. To compile under build system, it must be enabled in
vendor/cm/config/common.mk or vendor/cm/config/themes_common.mk (this was
requested in change http://review.cyanogenmod.org/#/c/26311/)

Themes were enabled in a new settings option. Under this setting the application
show the user the available themes installed in the system.

--------------------

For build new themes, developers should:

 - Create a new package that contains an activity with:
       * Permission: com.cyanogenmod.filemanager.permissions.READ_THEME
       * Action: com.cyanogenmod.filemanager.actions.MAIN_THEME
       * Category: com.cyanogenmod.filemanager.categories.THEME
 - Define the themes_ids, themes_names and themes_descriptions arrays-strings
   definitions for the themes that the package support.
 - Create a xxx_theme.xml for every theme that the package support, where the
   xxx is the id of the theme. Put your resources in this file, prefixing the
   resource with the id of the theme (xxx_). For a list of all supported
   resources see theme.xml in res/values of CMFileManager project.

-------------------

Other fixes:

 * Protect console buffers from NPE
 * Fix code style of xmls (layouts, drawables, ...)

Patchset 2: Fixed code style and added Christian suggestion
Patchset 3: Added forgotten READ_THEME permission check as described in the
            note above.
Patchset 4: Use centerInside in theme preview for better image fit

Change-Id: I4142da6d9ed1b06318e47ff9c05f9a874c62f3ae

1 files changed, 3 insertions, 0 deletions

diff --git a/proguard.flags b/proguard.flags
index 6fa82ecd..6f046926 100644
--- a/proguard.flags
+++ b/proguard.flags
@@ -53,4 +53,7 @@
 -keep public class * extends android.preference.PreferenceFragment {
   public <init>(...);
 }
+-keep public class * extends android.preference.Preference {
+  public <init>(...);
+}