I was not able to take a look at it yet, because you uploaded it on rapidshare. Please upload it smewhere else, as rapidshare only allows very restricted downloads to non premium mebers, and is overstrained at the moment. However, your patch won't get implemented anyway, if it is written for 0.5.x sources, as this is not the version teeworlds is developed from, currently. If you want supply patches for the next release, adjust them to the sources in the refactor branch(which is going to be the next release). And of course you don't have the rights to upload on the svn repository, if everyone had, guess what shit some people might do... . Finally I'm not really sure if this is needed, because your "trigger buttons" which you described above, are almost the same that can be achieved using the exec commad.
Example:
mode_1.cfg:
bind p exec "mode_2.cfg";bind mouse1 "+fire;emote 2"
mode_2.cfg:
bind p exec "mode_1.cfg";bind mouse1 +fire
and in console:
This will result in exactly the same functionality, as you described it.
About the general thing: I don't think it is neccessary, the only thing you have in advantage to using normal binds is that you have a description. As you probably would define your own actions, you should know what they do anyway(and if you bind them, you don't see the description anymore, so no need for it).
Also I believe, like grummi, that recursions are possible, the way he described it. I don't think there is a way to get around it here.
All in all my opinion is, it should not be included.