Combinatorial distance calculation module added. Only SCJ distance is implemented as of now

Now from BreakpointGraph one can output genomes as grimm of their fragments, respecting fragments orientation

Utils module is added, implementing some often used operation with standard python data structures

Kbreak now being applied to BreakpointGraph preserves information about regular vetices that are being affected; previously if the only edge to vertex  has been removed by the kbreak, the vertex was removed as well, and introduced again later on only by its name, thus loosing the information about any internally data, stored in the vertex object

BGEdge and BGVertex not have an ability to store additional information.

Respective test suites have been properly updated