fix #143: Update documentation with falling edge trigger
Cleanup: Correct Avalon master double-access due to waitrequest
Added missing newlines at end of files

This fixes g++ compiler warnings.
Remove un-needed const qualifiers on function return types

For g++ (GCC) 4.1.2, this fixes warnings like
cocotb/include/gpi.h:164: warning: type qualifiers ignored on function return type
Merge pull request #166 from FinnG/master

fix #143: Update documentation with falling edge trigger
Merge branch 'gcc_warning_cleanup' of https://github.com/tjora/cocotb into tjora-gcc_warning_cleanup
Merge branch 'tjora-gcc_warning_cleanup'
Cleanup: Improve error reporting for invalid coroutines
Issue #161: Cleanup some rather naff inheritance
Cleanup: Create hierarchical object for VPI structures
Issue #144: Dynamic loading in now done in our libs to the existing windows work needs enhancements to support dlls, this is the start of this
Issue #144: Add back -fpic for Linux builds
Issue #144: split dlopen from gpi_embed into a util lib, first steps to do windows dynamic loading implementation
Issue #144: Taken some direction from "elgorwi" and allowed the extenstion for a shared lib to be based on the OS
Issue #144: Do not call back down to Gpi on init failure, notify via return code. Fixes backwards linking with windows
Issue #144: Push the calling of gpi_get_root_handle up to Python so that it calls via the simulator module. This means that we not not have to link the embed lib against the gpi lib for this symbol
Issue #144: Moved looking for symbol into libcocotbutils and call gpi_embed_event rather than embed_sim_event
Issue #144: Include header macros to state that the functions are external on windows
Issue #144: Makefile changes to allow subset of interface libs to be built depending on
what the sim provides. This is mainly for windows where unresolved symbols in a lib are
not allowed to be resolved at run time. So for instance VHPI can not be built against
icarus on that platform.
Issue #144: Allow the path of a file to be passed to simulator in native format even if the shell uses a different format to do operations