Add SPOBC

This PR changes IFOC to a more versatile SPOBC. Among other things:

1. Adds nSequence marker to the issuing transaction which corresponds to 0,0,0,0,0,1 as the first 6 bits of the 32 bits that nSequence takes up. This corresponds to the nSequence value to 0x07ffffff instead of the normal 0xffffffff

2. Allows transfer in position other than the first. This is to allow for atomic swaps, which can be very important for smart property.

The change in the test is that the constants used throughout the tests were moved to lib_test.go.