I haven't read anything that's gone before about this subject, so feel free to lambast me for my unoriginality and laziness, but the problems raised by halfbat are clearly serious problems and within the rules as written.
I think, in a ponderous way, waiting to be shot down, that rather than adding a new combat action called Close, as per the wiki, if you read the definition of 'adjacent' (as per the close combat attack option) as anything within your movement rate then this all sorts itself out.
To me, any close combat attack can imply a degree of movement, not to mention the reach of your weapon.
I think that the move and sprint options are merely there to quantify the act of moving and sprinting in relation to everybody else's actions when said characters are not involved in melee (i.e how long it takes and how far you get). They include rules for the ramifications of moving through someone else's reach (i.e. free attacks), so this makes sense to me with just a little tweak, rather than a new Combat action.
It also seems to allow for anything with a larger movement stat to chase down or intercept anyone trying to do something clever or sneaky, which also seems to make sense to me. It's sort of like an area of influence dictated by your movement rate.
Have to tread carefully or before I know it I'll be playing Harnmaster...
