Solve beam on Initialization

[JJCoding01]

Add ability (automatically?) to solve a beam on the same line it is initialized.

For example, the following is not currently possible, but would be convenient.

beam = Beam(...).solve()
# further analysis on beam, ie
beam.plot()
...

Maybe even solve the beam automatically when it is initialized so that all you need is

beam = Beam(...)

# analyze beam