Autotarget toggle and attached template fixes

Features

Add a toggle to force no autotargeting for a given spell template in dnd5e. Closes #102.

Bug fixes

Address "endsWith" function not defined when using "attach to caster" in dnd5e. Closes #101.
Switch to storing a module-specific flag on active effects representing an attached template. Avoids conflicts with other modules that use the effect origin. Closes #102.

Full Changelog: 0.7.5...0.7.6