The UQM source now has a concept of input context for melee control.

A base InputContext structure is defined in battlecontrols.h. It defines
the common fields of all the specific structures for each control method.

Among these fields is a BattleInputHandlers structure, which defines the
functions which handle various input actions for melee, such as frame input,
selecting the next ship, and querying readiness at the end of a battle.

Structures ComputerInputContext, HumanInputContext, and NetworkInputContext
are "derived" from InputContext and can contain additional fields for the
specific control method.

