(CMAKE ROSE) Add DLL import/export symbols

This allows almost all of the ~100 tutorial executables to compile
and link successfully on Visual Studio.  The linker errors that remain
are due to the fact that edg33.lib is not yet available for download.

This commit also fixes the C2244 compile errors that were emitted
from midLevelRewriteInterface.h.
(CMAKE ROSE) make src/util a separate library

This separation resolves a problem that was caused by the fact
that both CxxGrammarMetaProgram and ROSE_DLL rely on some of the
code with src/util.  We define a new symbol while building the
roseutil library: ROSE_UTIL_EXPORTS.

Other changes within this commit:
* ensure that BitVectorRepr.h is compiled within the roseutil library.
* don't regenerate rose_paths.C unnecessarily
* enable building of AST file IO on Windows
(CMAKE ROSE) warn when pthreads aren't available
(CMAKE ROSE) conditionally compile sqlite3x

Only descend into the sqlite3x subdirectory if SQLite3 is available.
(CMAKE ROSE) conditionally compile some tutorials

sharedMemoryTraversals depends on pthread.h
codeCoverage depends on sys/time.h
(CMAKE ROSE) reorganize build output

Organize build output into a single bin directory and a single
lib directory.  This is the easiest solution for Windows .exes
to be able to find their needed .dlls.
Merge branch 'cmake_config_options' of https://github.com/zackgalbreath/rose into cmake_config_options