Add inline weapon command

[Azurelol]

• Adds a command to apply effects on a given actor's weapon. If they have more than one weapon equipped it brings up the dialog to choose which to apply. Once the weapon alteration effect has been applied onto the item, it applies a linked effect on the actor which tracks that of the item. When the effect on the actor is removed, it will likewise remove it on the item.
• Refactors the effect classes to delineate responsibility lines, moving several classes and functions out of the existing inline-effects file onto their separate files for clarity.
• Added the Effects definition which should contain the bulk of the methods for dealing with active effects in the system. This is a first pass on that cleanup as I did not want the PR to get any bigger.
• Fixes bug with evaluating expressions that was introduced in the check expression support feature.