Background work for issue #125: C HAL, SWIG wrapper, IO module
Issue #125: Simple test showing cocotb.function and unmodified HAL
Issue #125: Document the new HAL example
Issue #125: Add instruction on running the example!
Issue #127: Refactor the gpi/vpi layer, functionality same as before change
Issue #127: Removed unused code
Issue #127: Add back some tracing for memory allocation
Issue #127: Add new common base file and header
Issue #127: Fix some errors
Issue #127: Move gpi to gpi_log, since it is log lib
Issue #127: Rename vpi_shim dir since this now has the implementations
Issue #127: Move gpi_vhpi to gpi_impl dir (does not compile)
Cleanup: do not show error if file is not there on clean
Issue #127: Tie into new structure
Issue #127: Make functions static and fix errors
Issue #127: Fix up VHPI implementation
Merge pull request #129 from potentialventures/Issue#125

Fixes #125: Add example of external/function decorators
Merge pull request #131 from potentialventures/Issue#127

Issue#127
Update GHDL makefile (still broken)
Fixes #132 - Break reference tree so GC can cleanup coros