Allows to build csharp solution in Travis CI.
Two platforms are added: OS X and Linux. There are difference in builds
on the platforms: on OS X CI make C++ unit-test, while on Linux it does not
do it due to timeout/out of memory.

Users can install the grammar by adding the files to their
`%AppData%\Roaming\Sublime Text 3\Packages\User` folder.
It's fairly simplistic, but should be a decent start.

PowerShell script fails AppVeyor CI build when cabal install emits
warnings.

The cabal version 1.20+ was required only for the --required-sandbox
flag. However since the make files are setting up the sandbox we know
that we are always building using sandbox. The current Haskell Platform
comes with cabal 1.18 so this way installing cabal update is not needed.

Mono MemoryStream internal implementation differs from .NET implementation
It does not have `InternalGetOriginAndLength` method. So the cloning
method changed to use mono implementation of MemoryStream
when the method `InternalGetOriginAndLength` is not found

Made the following changes for the open source AppVeyor plan which
runs on very slow and memory limited VMs:
- Limit ghc heap size to 192MB when installing dependencies
- Use `appveyor DownloadFile` instead `Start-Download`
- Download Boost in the smaller 7Zip format
- Cache cabal sandbox and boost download
- Disable C++ build

Since C++ build is disabled we don't need to extract Boost and the build
is on the edge of time out.

This allows include directories to contain spaces.

This ensures that the MSBuild targets and gbc work when a .bond file or an
import directory has spaces in the path.

When support for import directories with spaces in their paths was
added, that inadvertently broke codegen when one ended with a trailing
slash. We add a trailing \. like we do for the output directory to fix
that.

When bonded<T> is serialized to untagged protocols like Simple Binary
it is first marshaled into a separate buffer using a tagged protocol and
then written as length prefixed blob to the untagged protocol.
OutputBuffer used for marshaling by default allocates 64KB which is
costly if the bonded<T> payload is small.

Unit tests take a long time to run in CI. Building all tests with
--collection-interfaces flag is somewhat wasteful because a lot of tests
don't use collections at all. Furthermore this way we only tested
collection interfaces together with properties. This change removes the
separate test configuration for --collection-interfaces and instead uses
concrete/interface collection alternatively for different .bond files in
Fields/Properties configuration. This way every schema is tested with
both interfaces and concrete collections and both are also tested with
fields and properties. This gives better coverage while eliminating
redundant identical tests in different assemblies.