Log Message:
Changes 2.4.1:
- Fix for Bug 2791 - Setup.py fails unnecessarily under Jython.
- Fixed license of SVG titlepage files in the context of Debian
  packaging, such that they allow for commercial use too (2985).
- InstallVersionedLib now available in the DefaultEnvironment context.
- Improves orthogonality of use cases between different Install functions.
- Added new configure check, CheckProg, to check for
  existence of a program.
- Fix for issue 2840 - Fix for two environments specifying same target with different
  actions not throwing hard error. Instead SCons was incorrectly issuing a warning
  and continuing.
- Add support `Microsoft Visual C++ Compiler for Python 2.7'
  Compiler can be obtained at: \ 
https://www.microsoft.com/en-us/download/details.aspx?id=44266
- Fixed tigris issue 3011: Glob() excludes didn't work when used with \ 
VariantDir(duplicate=0)
- Fix bug 2831 and allow Help() text to be appended to AddOption() help.
- Reimplemented versioning for shared libraries, with the following effects
- Fixed tigris issues 3001, 3006.
- Fixed several other issues not reported to tigris, including:
  issues with versioned libraries in subdirectories with tricky names,
  issues with versioned libraries and variant directories,
  issue with soname not being injected to library when using D linkers,
- Switched to direct symlinks instead of daisy-chained ones -- soname and
  development symlinks point directly to the versioned shared library now),
- New construction variables to allow override default behavior: SONAME,
  SHLIBVERSIONFLAGS, _SHLIBVERSIONFLAGS, SHLIBNOVERSIONSYMLINKS,
  LDMODULEVERSION, LDMODULEVERSIONFLAGS, _LDMODULEVERSIONFLAGS,
  LDMODULENOVERSIONSYMLINKS.
- Changed logic used to configure the versioning machinery from
  platform-centric to linker-oriented.
- The SHLIBVERSION/LDMODULEVERSION variables are no longer validated by
  SCons (more freedom to users).
- InstallVersionedLib() doesn't use SHLIBVERSION anymore.
- Enchanced docs for the library versioning stuff.
- New tests for versioned libraries.
- Library versioning is currently implemented for the following linker
  tools: 'cyglink', 'gnulink', 'sunlink'.
- Fix to swig tool - pick-up 'swig', 'swig3.0' and 'swig2.0' (in order).
- Fix to swig tool - respect env['SWIG'] provided by user.