Added convenient create functions for Java/C#.

Bug: 15777857
Tested: on Linux and Windows.

Change-Id: I25db724349e2c801bb0e41137540507acd57cd03
Add enum name lookup method to Java/C# enums

Tested: on Linux for Java and C#

Bug: 15781151
Change-Id: I7cb97bcc01d986cac2b24aaf7cb29521ddaa2f6b
Generate headers from spec, add option for installing targets

Change-Id: I16ddb06e887e618fa871e842054115909fbf235c
Support for required fields.

Change-Id: I560c7ca11b3d665eecafb528f3737b7e139ca9b0
Tested: on Linux and Windows.
Added option to flatc to generate dependent header statements.

Bug: 17322776
Change-Id: I3a4d3cb4ccd40bc3200a87653aa0ab8ecb90ce60
Tested: on Linux.
Made flatc error messages look like what other compilers output.

Looks like MSVC on Windows and like gcc everywhere else.
For enhanced IDE clickability.

Bug: 17208371
Change-Id: Ie3e02658fccd3edfd464b4bacf4bc68c613a8570
Tested: on Linux and Windows.
Enums in C++ are now strongly typed.

Accessors and constructors now take enum types rather than ints.

Bug: 16570507
Change-Id: I4b50fd64ad2e662ea2481bc0ccea784326fb31c0
Tested: on Linux and Windows.
Fix vector of strings for Go

Mirrors Java patch 39d4b7e2bf

Change-Id: If8d0ab29f6eb508a156d468aeb0a9d5410149e53
Improve install rules and add support for building FlatBuffers inside another project

Generate the files needed by another cmake driven project to
find_package(FlatBuffers), either external or when both projects are
subdirectories of some larger project.

Support 3 methods of using FlatBuffers
find_package(FlatBuffers) - pointing to the INSTALL location
find_package(FlatBuffers) - pointing to the BUILD directory
add_subdirectory(FlatBuffers) - where the project using
FlatBuffers can simply set FlatBuffers_DIR to the build subdirectoy
The main difference is that the build dir versions need the source tree
include locations instead of the install tree.

We generate the following files in the BUILD directory
as well as the INSTALL tree

FlatBuffersConfig.cmake
FlatBuffersConfig-version.cmake
FlatBuffersTargets.cmake