Merge pull request #23 from morevnaproject/master

Random fixes
Update Autoconf Boost detection scripts to the latest version
Tell build script to use synfig-core includes from the source dir. This should improve rebuild speed for synfig-studio.
Fixed problem with drag'n'drop files. Now synfig does import of dropped
files instead of creating a text layer with file URI.
Note: Non-ASCII characters in filenames or paths are not supported yet.
Import files by drag'n'drop now supports non-ASCII characters in
filenames and paths.