Propose to merge LinkWranger_Acutioneer and LinkWrangler_Companion plugins into the main LinkWrangler download, and to add other plugins.

Propose to add a subfolder Plugins

Need to trigger plugins loading after all other (non-LOD) AddOns have loaded, probably during "PLAYER_ENTERING_WORLD", however do not want each plugin to have to create its own (one-use) event frame...

Propose to create a new callback option to allow plugins to piggyback off LW's event handler.

b801b63 implements new "gameactive" callback

095d5a1 implements LibExtraTip plugin (previously part of https://www.curseforge.com/wow/addons/linkwrangler_auctioneer) as first test plugin

e5120e7 implements hooks from LW link buttons into AucAdvanced Snatch and Appraiser (the other half of old LinkWranglerAuctioneer plugin).

09f6e7f updates to documentation, also update version number to 2.10.

Other AddOns will be able to test for LinkWrangler.Version >= 2.1 to see if they can use the "gameactive" callback (though obviously not needed for plugins bundled in LinkWrangler download).