Rework "paths" settings loading and card database loading

 * main.cpp: removed path checking and db loading
 * card database: merge card loading methods into a single one
 * settings cache: take care of returning safe paths for decks,
replays, etc..
 * main window: if db loading fails (eg. first run), propose to run
oracle

NSIS: propose to run cockatrice instead of oracle

Rework card database loading

 * Move carddatabase-related method out of deckeditor tab
 * Load cards in another thread and render them progressively
 * Optimize database reload after enabled sets change

Fix deck editor column width

 * removed the noCard hack.
 * getCard() no more creates cards instead of just returning existing
ones
 * Fix the “edit tokens” dialog.
 * PictureLoader: avoid trying to download twice the same card
 * PictureLoader: correct return of card background
 * AbstractCardItem: avoid recalculating card color at every paint

Use a different file to save custom tokens

Misc required improvements

 * Use nullptr;
 * Refactor CardInfoWidget to use CardInfoPicture and CardInfoText
instead of duplicating code;
 * Added CardInfo::getColorChar()
 * Fixed some potential crashes
 * removed dead code related to CardInfoWidget
 * Don't require a restart after adding a new custom sets file
 * Bump CMake requirements to 3.1

travis-dependencies.sh

@@ -11,9 +11,10 @@ if [[ $TRAVIS_OS_NAME == "osx" ]] ; then
   brew upgrade cmake
 
 else
-
   # common prerequisites
+  sudo add-apt-repository -y ppa:smspillaz/cmake-master
   sudo apt-get update -qq
+  sudo apt-get -y purge cmake
   sudo apt-get install -y libprotobuf-dev protobuf-compiler cmake bc
 
   if (( QT4 )); then
@@ -28,15 +29,7 @@ else
 
   # prerequisites for tests
   if [[ $BUILDTYPE == "Debug" ]]; then
-    if [[ $DIST == "precise" ]]; then
-      sudo add-apt-repository -y ppa:george-edison55/precise-backports
-      sudo apt-get update -qq
-      sudo apt-get install -y cmake cmake-data libgtest-dev
-    else
-      sudo add-apt-repository -y ppa:george-edison55/cmake-3.x
-      sudo apt-get update -qq
-      sudo apt-get install -y cmake cmake-extras libgtest-dev
-    fi
+    sudo apt-get install -y libgtest-dev
 
     sudo mkdir /usr/src/gtest/build
     cd /usr/src/gtest/build