Refactor InstrumentBasicBlocks to not use SplitAfterCall.

This results in more logical grouping of instrumentation steps, regarding
control flow within functions versus that between functions.
Remove references to SplitAfterCall in RemoveCFGAliasing.
Update documentation to remove references to obsolete passes.
Remove obsolete SplitAfterCall pass.
Merge pull request #27 from hermannloose/fix-26

Refactor to make SplitAfterCall obsolete.

This fixes #26.