list of user-visible changes between releases of libing

[0.2.0]
* bump soname
* new Config class
    - more flexible architecture
    - supports both libxml2 and xmlscope libraries
* fixes, new operators in PerlRE,RegularExpr classes
* rewrite exceptions hieracly
* added color streams feature into Color object
* new FileLock object
* FileSystem object replaced by DirStream
* some new helper functions
* added new tests
