Features for 0.3

[iainctduncan]

Discussion of list of what will go in 0.3 as new:

• low priority thread delays
• app level gc enable/disable
• execution of code messages directly (no eval string necessary)
• threading macros
• fixes to send (allow list)
• (outs)
• misc s74.scm updates
• tested to work in max for live
• optional live-api scheme code
• ? function to make objects ?