Subtle bug, the provision of a start vector means chains were not being placed horizontal. By setting the default bond vector as static we can check if the caller has really provided a vector to use. If the default was provided we can now still place the chain horizontal.

Signed-off-by: Egon Willighagen <egonw@users.sourceforge.net>
Include hydrogens when counting degree. In practice this means carboxylic groups are always placed with the carbonyl pointing up or down when at the end of a chain.

Signed-off-by: Egon Willighagen <egonw@users.sourceforge.net>
Hydrogen count needs to be set for test.

Signed-off-by: Egon Willighagen <egonw@users.sourceforge.net>