CsgPrimitive: Should return true from isPrimitive

Oopsie! Copy-paste is bad.

Signed-off-by: Celelibi <celelibi@gmail.com>
CsgTree: Primitive / Operation condition inversion

Oopsie! Coding late is bad.

Signed-off-by: Celelibi <celelibi@gmail.com>
csg: Be more specific when printing the messages

Now the debug messages are prepended with the class name.

Signed-off-by: Celelibi <celelibi@gmail.com>
csg and InterfaceCSG: switch to debug mode

Add debug to the targets and replace flag -g with -ggdb.

Signed-off-by: Celelibi <celelibi@gmail.com>
CsgTree: Draw a proper ASCII tree

The code from the prof was completely fucked up. Here is a working
version.

Signed-off-by: Celelibi <celelibi@gmail.com>
CsgTree: Add a few sanity checks

When joining two nodes, ensure we don't try to join a node with itself
and that the nodes we're joining are not yet involved in a tree.

Signed-off-by: Celelibi <celelibi@gmail.com>