ALS injector example

[qianglbl]

In a real machine like the ALS injector,
there is a middle layer that contains control variables for the EPICS system.

Where should these variables be placed within PALS?

[qianglbl]

remove "length" line for START and END

[qianglbl]

@DavidSagan PALS header added. Also, I don't understand why we should remove "length : 0.0" for the START and END elements?

[qianglbl]

@DavidSagan The two length lines for START and END elements were removed.

[DavidSagan]

@qianglbl It is looking good. The only thing missing now is a Lattice construct:

- ALS_Injector
    kind: Lattice
    branches:
      - LTB

[qianglbl]

@DavidSagan Thanks and added the Lattice construct.

[EZoni]

@qianglbl

Do we want to include control variable information in this PR? If not, what does this example alone, as is, describe?

[qianglbl]

updated quadrupole values in the ALS injector example.

[cemitch99]

Let's change the name of this PR to "ALS injector example" or something similar.

[EZoni]

FYI, I will push a small style change to this branch.

[qianglbl]

@DavidSagan added initial beam sigma matrix information.