The version that meshes a full annulus and accepts a flavour flag was not
flagging all nodes correctly. The mesh for the full annulus in this version
is generated by meshing a rectangle in polar coordinates. This is then
glued together by removing duplicate nodes and edges at the interface
phi = 0 = 2*pi.

However, meshRectangle flags all interior nodes as 0 and all nodes on the
boundary as 1. This was not corrected for at the internal interface. Thus,
interior nodes with phi = 0 retained their flag of 1.

This commit implements a different approach to flagging. We mark all
interior nodes as 0, all nodes on the inner (rhoMin) boundary as 1 and
all nodes on the outer (rhoMax) as 2. While doing so we implicitely also
fix the bug.

For convenience the commit implements two new private member functions
- meshInfo::deduceEdgeFlagsFromVertices()
- meshInfo::deduceFaceFlagsFromVertices()
These will (re)set all flags for the corresponding entity based on that
of their two resp. three vertices. If those flags are different the
argument value flagInconsistent is used instead.

Commit also updates the second version for meshing a full annulus to set
the flags as {0,1,2}. The new convenience methods allowed to remove also
the deriveEdgesForFullAnnulus() helper function.