Make correction to README (#36) and add InteractiveDebug function.
Check for errors when running arbitrary code.

The stack is only cleared if the call is successful, so that in errors one can get the error string at index -1.
Merge branch 'Dante12129-patch-1'
Update README.md

in "registering class member variable", the example is written with "bar.set_x(-4)"
it doesn't work, it should be : "bar:set_x(-4)"
Merge pull request #42 from GuilhemBernard/patch-1

Update README.md
Add support for returning pointer and reference types from C++ functions registered with lua
Fix compilation with Lua 5.1
Add new State constructor allowing to work with existing lua_State.
Change tabs to spaces and move constructor getting lua_state to the right place.
Merge pull request #44 from rafalh/ctor-lua-state-patch

Add new State constructor allowing to work with existing lua_State.
Merge pull request #43 from rafalh/lua51-support

Fix compilation with Lua 5.1
Add MetatableRegistry to support binding registered metatables to userdata.
Delete unnecessary comments in MetatableRegistry.h
Fix userdata implementation and add relevant new tests.