core: Properly enable C++11

Problems with previous approach:
1. It broke build of libiris's plain C parts on all systems.
2. It was incompatible with GCC 4.6.
3. It was incompatible with MSVC.

Signed-off-by: Bartosz Brachaczek <b.brachaczek@gmail.com>
gui: also store CurrentGroupTab in GroupTabBarConfigurator

Signed-off-by: Rafał Malinowski <rafal.przemyslaw.malinowski@gmail.com>
gui: added groupFilters method to GroupTabBar

Signed-off-by: Rafał Malinowski <rafal.przemyslaw.malinowski@gmail.com>
gui: use GroupTabBarConfigurator also to store configuration

Signed-off-by: Rafał Malinowski <rafal.przemyslaw.malinowski@gmail.com>
gui: store order of group tabs in GroupTabBarConfigurator

Signed-off-by: Rafał Malinowski <rafal.przemyslaw.malinowski@gmail.com>
gui: load group tab sequence in GroupTabBar at start of application

Signed-off-by: Rafał Malinowski <rafal.przemyslaw.malinowski@gmail.com>
gui: remove unused members from GroupTabBar

Signed-off-by: Rafał Malinowski <rafal.przemyslaw.malinowski@gmail.com>
gui: added GroupTabBar::setInitialConfiguration method

Signed-off-by: Rafał Malinowski <rafal.przemyslaw.malinowski@gmail.com>
gui: renamed GroupTabBarConfigurator::configuration to loadConfiguration

Signed-off-by: Rafał Malinowski <rafal.przemyslaw.malinowski@gmail.com>
gui: restore old behavior of ungroupped tab

Signed-off-by: Rafał Malinowski <rafal.przemyslaw.malinowski@gmail.com>
gui: fix d&d in GroupTabBar

Signed-off-by: Rafał Malinowski <rafal.przemyslaw.malinowski@gmail.com>
gui: fix ungroupped tab behavior

Signed-off-by: Rafał Malinowski <rafal.przemyslaw.malinowski@gmail.com>
gui: restore old name of configuration variable: ShowGroupAll

Signed-off-by: Rafał Malinowski <rafal.przemyslaw.malinowski@gmail.com>
talkable: fix interface of GroupFilter* classes

Signed-off-by: Rafał Malinowski <rafal.przemyslaw.malinowski@gmail.com>