Fixes #5.

Mark vertex_texcoords_available() as const

See merge request !23

Property map hfh int support

See merge request !22

Fixed CI on Windows

Closes #4

See merge request !21

enable ```__cplusplus>=201103``` guarded code on recent MSVC.

See merge request !19

MSVC does not define __cplusplus as >=201103 yet.
An older version of MSVC is probably sufficient, but I can't test that.

Fix cppchecks

See merge request !18

disable file_converter if boost is not found.

See merge request !17

Fix doxygen

See merge request !16

Added doc ci target

Switched message style to make clear it's not an Error.

See merge request !15

Update logo

See merge request !14

Break compatibility with pre-C++11, implement make_unique

@moebius, @lyon - if I understood you correctly, OVM and OM shall also be C++-11-and-up? If so, we can avoid some more ifdef complexity by just breaking compatibility now.
(If not, I'll revise my make_unique patch)

Let me know if you'd prefer separate PRs.

See merge request !13