Please install short term trend on plot functions not using geom_gls because they are <30 years

[sgaichas]

As noted in #165 (comment) some plot functions have geom_gls commented out. This is likely because they have fewer than 30 years of data to plot. For datasets that don't meet the length criterion for using geom_gls, we do want the option of using geom_lm.

So far this applies to the commercial diversity datasets that I have seen, but there are others.

[BBeltz1]

I've completed another sweep of the indicators and added short term trend analysis to the following:

• plot_commercial_div
• plot_ichthyo_diversity
• plot_nao
• plot_ne_inshore_survey
• plot_observed_sharks
• plot_slopewater
• plot_wcr
• plot_wind_revenue

[BBeltz1]

There may still be others, so please let me know if you notice any other plots you want short term trend applied to. Thanks.