Quickbook: Rough stab at outputting dependencies. Refs #6691

Adds `--output-deps` flag. To write out dependencies to `deps.txt`:
{{{
quickbook --output-deps deps.txt source.qbk
}}}

If `--output-deps` is specified, quickbook won't generate an output file
unless one is specified with `--output-file`. If there is an error it
will return an error code, but it will still write out all the opened
files.

Known issues:
- If the same file is included/imported twice it may or may not list it
  twice. Should be consistent.
- Doesn't include SVG files. It probably should as they can affect the
  output.
- Need to check some of the path issues for things such as xinclude
  paths which depend on the output file path.
- Needs tests and documentation.

svn path=/trunk/tools/quickbook/; revision=77442
Quickbook: Track dependencies in state. Refs #6691

- Use cananoical filenames where possible.
- Remove duplicates.
- Include SVG files.
- Less hacky.

svn path=/trunk/tools/quickbook/; revision=77490
Filesystem no longer provides a VC++ Solution for VC++ 9

svn path=/trunk/tools/quickbook/; revision=77560
Quickbook: Further dependencies development. Refs #6691

- Include relevant locations on path where file wasn't found.
- Improve `include_search` while I'm at it.
- Normalize paths for non-existent files.
- Tests, not integrated with Boost.Build yet. Needs to check that
  python is available then run the script with the location of the
  quickbook executable.

svn path=/trunk/tools/quickbook/; revision=77598
Quickbook: Use container forwarding for gcc/darwin.

It's usually safe. Especially since we're controlling the build.

svn path=/trunk/tools/quickbook/; revision=77830
Quickbook: Deal with checked paths that aren't present. Refs #6691.

I think that the dependencies should just be files that were loaded, so
I changed it to do that, but added an extra (hidden for now) option to
list all paths that were checked, staring with a `+` for files that are
present, and `-` for files that are absent.

Also fixed a bug with the path resolver.

svn path=/trunk/tools/quickbook/; revision=77973
Quickbook: Remove intrusive_base. Refs #6794.

svn path=/trunk/tools/quickbook/; revision=77998
Quickbook: Set version for release.

svn path=/trunk/tools/quickbook/; revision=78727
Quickbook: Fix documentation.

Was using a feature I haven't implemented yet.

svn path=/trunk/tools/quickbook/; revision=78728
Quickbook: Backdated changelog for 1.5.8.

Oops, I completely forgot to write this up at the time.

svn path=/trunk/tools/quickbook/; revision=82573
Quickbook: Describe new 1.6 tags.

svn path=/trunk/tools/quickbook/; revision=82589
Quickbook: Fix typo.

svn path=/trunk/tools/quickbook/; revision=83018
Bump version number.

svn path=/trunk/tools/quickbook/; revision=83115
Convert to use boost::string_ref

svn path=/trunk/tools/quickbook/; revision=83116
Source map tests.

svn path=/trunk/tools/quickbook/; revision=83117
Store indentation change in source map.

Used to infer it when required, which could go wrong.

svn path=/trunk/tools/quickbook/; revision=83118
Fix `to_original_pos` for indented blocks.

svn path=/trunk/tools/quickbook/; revision=83119
Clean up poorly overloaded 'add' method.

svn path=/trunk/tools/quickbook/; revision=83120
Extract duplicated find_section code.

svn path=/trunk/tools/quickbook/; revision=83121
Fix mapped position when breaking up indented code.

svn path=/trunk/tools/quickbook/; revision=83122