EC-ISA: add intelligent table cache

The EC decoding uses decoding tables configured for the current failure situation. Between individual calls to the CODEC instance these failure
configuration might change. To avoid to recompute and store the decoding table before each decoding step a table cache is used to retrieve already computed
decoding tables. The table cache is split into a cache for cauchy and reed-solomon tables. Each cache is dimensioned to host all possible decoding tables for a maximum k=12,m=4 configuration. The cache is populated on the fly since under normal conditions most decoding tables are never used. If larger k,m configurations are used the cache might overflow. In this case it behaves as an LRU cache keeping the last recently used decoding tables and flushing the oldest tables first.
EC-ISA: avoid usage of table cache lock outside the class implementation by introducing the setEncodingTable/setEncodingCoefficient methods

For encapsulation purposes we avoid to use the cache serialization mutex outside the cache implementation. We achieve this by introduction of a table/coefficent setter function resolving races internally (serveral threads updating the same table/coefficients concurrently).