Use Chris's code to get ALPI calculated (hasn't been updated since 2015)

[andrew-edwards]

Another SOPO-motivated request. Lots of mention of the Aleutian Low in the talks (except, ironically, Bridgette's about the Gulf of Alaska).

[andrew-edwards]

• read through ?alpi
• go through current data-raw/.R
• run Chris's new code
• work out how to incorporate into the existing, saving as alpi_new
• compare historical values, making sure that alpi and alpi_new match
• replace package alpi with alpi_new
• update help
• re-run vignette and README, as table should get updated
• tell Chris and others.

[andrew-edwards]

Did the updates using Chris's values that he sent me (up to 2022).
To continue forward I have code saved locally in raw-data/coastwide-indices/alpi-surry/ to dig into. Chris thinks the websites have since changed, so may require a bit of work. alpi-update.R was used for the current update.