Also test remote_actor() with std::string.
Merge pull request #99 from mavam/topic/remote-actor-str-test

Enhance remote_actor() unit tests
optimization in serialization layer

this patch removes redundancies and reduces string comparisons by
using session-dependent type IDs rather than sending type names
use binary serialiization for floating points
add_tuple_hint => announce_tuple
added trivariant class

a trivariant is (a) invalid, (b) empty, or (c) one of its variadic types;
this new class is introduced to hold the result of a partial function
trivariant => optional_variant

this patch replaces trivariant with optional_variant which can offer the
same semantics when used as optional_variant<void,...>
fixed uniform_type unit test
updated gitignore file
implemented proper operator= for optional_variant
improved logging of broker-related functions
option => optional

this patch renames `optional` to `optional` in advance of porting
libcppa to boost
removed default-ctor of option & added cppa::none
added optional<void> specialization
fixed tl_filter_type
forward results of pattern matching callbacks

this patch enhances the pattern matching of libcppa, i.e., the result
of invoked callbacks is forwarded to the caller
removed unused typedef
fixed proper_matrix example
fixed opencl unit test
removed unused constexpr variable