Finalize the feature, ready for QA

res/ui/explorer_tab.ui

res/ui/wot_tab.ui

src/sakia/core/graph/explorer_graph.py

src/sakia/gui/graphs/explorer_tab.py

src/sakia/gui/graphs/graph_tab.py

src/sakia/gui/graphs/wot_tab.py

src/sakia/gui/widgets/search_user.py

src/sakia/tests/unit/gui/views/test_base_node.py

src/sakia/tests/unit/gui/views/test_explorer_edge.py

src/sakia/tests/unit/gui/views/test_explorer_node.py

src/sakia/tests/unit/gui/views/test_wot_edge.py

src/sakia/tests/unit/gui/views/test_wot_node.py