Major Improvements

The following improvements have been made:
- rewrote the GF256-Math with lookup-tables -> everything is now ~5x faster!
- all classes and methods are now documented
- implemented "Unconditionally Secure Robust Secret Sharing with Compact Shares (*USRSSwCompactShares*)"
- added additional secure and also faster random-number-generators (*CTRPRNG*, *StreamPRNG*, *SHA1PRNG*; some of them based on the *bouncycastle-API*)
- reconstruction algorithms are now exchangeable (*ErasureDecoder*, *BerlekampWelch-Decoder*)
- cleaned up code and removed redundancies with new helper-classes
- expanded unit-tests
- resolved some tickets (see below)
- added some *TODOs* for  newly discovered problems

In addition the following issues have been resolved:
- **ShareSerializer (#1)**
    - ShareSerializer now supports shares of all types
    - Share has been changed to support multiple types (for example Rabin-Ben-Or needs to be *RABIN_BEN_OR*, *KRAWCZYK*, *REED_SOLOMON* and *SHAMIR* at the same time!)
    - added unit-tests
- **Berlekamp-Welch-Decoder (#3)**
    - implemented basic Berlekamp-Welch-Decoder (reconstruction algorithms are now also exchangeable)
    - added unit-tests

*(I kind of forgot to do intermediate commits ...)*