chore(lua): rename init_* functions to open_*

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
feat(lua): expose options object in the Lua bindings

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
fix(lua): problem when compiling with clang++

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
style(lua): add missing include

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
fix(lua): safe_function_wrapper

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
refactor(lua/name): improve name bindings for Lua

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
refactor(lua/options): improve options bindings for Lua

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
refactor(lua/name): improve name bindings for Lua

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
refactor(lua): add goodies for accessing Lean values on the Lua stack

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
feat(lua): expose s-expressions in the Lua bindings

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
feat(lua/sexpr): improve sexpr Lua bindings

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
test(lua): add more s-exprs Lua tests

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
fix(lua): expose missing functions

Signed-off-by: Leonardo de Moura <leonardo@microsoft.com>
chore(travis): update to use mxe-gcc-4.8.2.tar.bz2

 - fix compatibility problem with cmake-2.8.12
 - update g++ version from 4.8.1 to 4.8.2
 - include lua