check requested pattern against list
Merge pull request #24 from btmills/master

fix reading beyond hash length
remove rescue block
Merge pull request #23 from jasonlong/generator-validation

Make sure requested pattern is valid
bumped version to 1.1.1
Change Pattern::PATTERNS to a frozen array of Strings

Pre @gregose's comment: https://github.com/jasonlong/geo_pattern/pull/23#discussion_r9952246

`to_sym` could lead to a DoS: http://www.ruby-doc.org/core-2.1.0/doc/security_rdoc.html#label-Symbols.
Merge pull request #25 from parkr/patch-1

Change Pattern::PATTERNS to a frozen array of Strings
bump to version v1.1.2
Fix missing hex_val conversions

In the mosaic squares pattern, vals were being sent as strings from
the hash without being converted to numeric form first. When val > 9,
for examples, opacity incorrectly ends up at its minimum value 37.5%
of the time.