Added TSManager per #36

Added timeseries manager - benefits thus far:
-removed unrelated coded from tstools.py
-changed stupid design decisions that passed ts reference back and forth
Changed rest of plugin to conform to #36 change
Fixed bug where custom options wouldn't disappear
Merge YATSM timeseries fix into branch
Missed one (last) self.ts reference
Added 'test_indices' option so GUI works for it
Fixed ugly f.close within a 'with open as f'; also some PEP8
Updated to latest YATSM version
Fixed bug and import convention for custom_form
Added LOWESS screen option, and work toward removed obs as metadata
Merging and prep work for dynamic metadata

Metadata right now is only changed on init of timeseries. Instead we
should also have the option of requesting an update. Will need to refactor
some code from controls_symbology.py into separate methods that can be
called by controller or something like that
Fixed bug when adding images from plot with symbology

If symbology was applied to the plot, we use mulitple lines for each color.
Since there are multiple lines for multiple subsets of the dataset, we can't
just use event.ind for the index. We instead need to get the X data for the
index of the line picked and match it up to find the correct index
Refactored some code and added multitemp screened metadata

- Refactored symbology plotter per 528f105e7c789b5d3a80ad6c3233bce9ac088b8f
- Now checks and lists which X values don't exist in the model (because they
were screened)
Updated for YATSM cloud screen fix
Fixed bug with datatypes of initial model parameters
Updated YATSM for LOWESS multitemp screening fix
Updated for bugfixes in YATSM