For selections that do not explicitely state a QueryFlag option, a default
query flag is used instead of 0. This is an extension to current behavior
and should have zero impact on existing code.

Adds the option to turn off coloring outside range given
by minv and maxv; this should actually be the default, but
clamp=True is the default for now to mimick old behavior.
The implementation is incomplete and only works for Entity
right now.

In Python, gfx.Gradient can now be initialized with a dictionary; for each
key: value pair, the key is a float between 0 and 1, and the value is either
a float triplet or a gfx.Color object.

In C++, Stop and StopList were moved into Gradient to avoid namespace
pollution. In Python, they were renamed to GradientStop and GradientStopList.
As a consequence, gui/pymod/scene/gradient_editor_widget.py has had a rename
of its GradientStop to MyGradientStop.

  - fixed continuous residue numbering (BZDNG-286)
  - fixed bug with empty lines
  - fixed bug with reading residue name in std format
  - write b_factor in EXT format
  - segment name is now cname instead of 'MOL'
  - fixed alignment of residue name in std format
  - add documentation
  - add unit tests
  - possibility to request EXT format

(BZDNG 288 and 289)

fixes BZDNG-284

PrimList now contains four specific rendering primitives: points, lines,
spheres and cylinders; lines and cylinders accept two different colors
for each endpoint, and cylinders support two different radii for their ends.
The rendering mode no longer has any effect, also, it is no longer possible
to change the radius of spheres and cylinders once they are added.

The python interface is much more sophisticated, using named arguments
for optional parameters.

The low-level cylinder routine in IndexedVertexArray was adjusted
accordingly

Extended STAR parser with better error messages and more test cases. Asserts are removed up to one single item.

Extended funtionality of the STAR format parser. Items may no be read as loops, to avoid redundancy in OnDataItem() and OnDataRow().