Fix: Added indention for case-block

We should indent this if we need a block inside a case-statement like
so, which is _much_ more readable for long switch(-case) blocks, as we do
not visually collide with the closing bracket of the switch block.
Merge pull request #20 from matthiasbeyer/fix-code_example_in_contributing_file

Fix: Added indention for case-block
Added include/libreset/hash.h

This adds the include/libreset/hash.h file for the export of the hash
type used by the library.
Added documentation note about handling the rs_hash type
Updated README.md file
use size_t instead of uint64_t for rs_hash type
Merge pull request #24 from matthiasbeyer/add-hash_util

Add hash.h hash utility
Merge pull request #30 from matthiasbeyer/update-readme

Updated README.md file
Add inclusion of amsmfonts package
Add note about disjunctive buckets
Add subsection about constraint on number of buckets
Add subsection about mapping to buckets
Add subsection about a bucket's substructure.
Add labels to sections