Add support for Intel 15, fix Glob Bug, and compiler path selection bug.

This patch fixes 3 issues:

- Adds support for Intel-15 so MSVC version can be auto-selected.

- Changes GLOB to path.glob as for some reason the GLOB rule always
fails when used in this context (discovered when testing this patch).

- Changes selection logic for target-types variable - previous code
used the value of PROCESSOR_ARCHITECTURE to detect this, but that
appears to only tell you which sub-system bjam is running in. For
example on my system bjam is a 32-bit app (default for an msvc build),
but I only have the Intel 64-bit compiler installed (under /intel64/).
New logic checks whether the intel64 compiler exists and uses that if
it is - Intel's installer won't install this on 32 bit platforms in
which case the glob fails and things fall back to the ia32-intel64
cross compiler when address-model=64 is specified.
Update expected error message wording.
Merge from develop.

Core changes:

- Multiple improvements in Python port, from Aaron Boman.
- Clearer error reporting for target name clases and invalid
  metatarget references, from Vladimir Prus.

Visual Studio:

- Initial support for Windows 8 phone and store applications,
  from Steve Gates.
- Faster builds, via caching setup script invocations,
  from Juraj Ivančić.
- Support for custom DLL manifests and dlls without import libraries,
  from Bernhard B.

Tools:

- Improved clang support, from Edward Diener.
- Support for Intel 15, from John Maddock.
Use feature name for better error output.
Remove return in favor of try...except return.
Remove unused import
Fix pathing issue. ARM's ar.exe didn't like the mis-matched path separators.
check_init_parameters: requirement should be a container.
command is always a sequence, always use extend().
Old style exceptions don't work.
Use __file__ variable for location.
Add module's location to loaded_tool_module_path_ dict.
Add C scanner
Miscellaneous improvements from Aaron Boman.

feature.py:

Use the feature's name in the error output. This helps in understanding the
error message.

project.py:

The original looked like the result of a bad merge as the return value was the
exact same as the return within the try...except block. The try...except
produces a better error message upon failure.

property_set.py:

The string module is unused.

virtual_target.py:

ARM's ar.exe would fail when passed a path to the -via file that had both
POSIX and Windows path separators. Normalizing the path on the target solved
the problem.

common.py:

The requirement parameter in check_init_parameters should be a container. The
original Jam signature marks it as a list with zero or more items. These
changes convert the requirement parameter to using only a container.

msvc.py:

The call to to_seq asserts that command is always some container. So, extend()
should always be used.

tools/rc.py:

Old style exceptions aren't allowed (at least in Python 2.7). This change just
uses the existing AlreadyDefined exception.

testing.py:

loaded_tool_module_path_ is empty upon initial import. Using the __file__
variable instead will always work (provided the import system doesn't change).
Add support for ranlib.
Block SIGCHLD during select.

Select was losing child termination signals so we explictly
block SIGCHLD during select, and unblock after select returns.
Tested on 256 core smp system, no hangs or zombies.  Thanks
to Alain Miniussi <alain.miniussi@oca.eu> for reporting this.
Fix a dependecy --> dependency comment typo.
Fix error message typo - same named targets with different properties.
Fix dependendency --> dependency comment typo.
Fix comment typos.