refactor: refactoring matchers.SequenceMatcher

[vvatanabe]

refactoring matchers.SpatialMatcher:

• Extracted part of the process within the execute function into a separate function.
• Applied google-java-format.
• Made the regular expression object LOWERCASE_PATTERN, UPPERCASE_PATTERN, DIGIT_PATTERN static to reduce the number of times it's created.
• Defined literal values used in methods and within the class as constants for readability and change management.
• Changed the regular expression's find function to matches function. (Switched from partial match to a complete match.)
• Defined SequenceType as an inner class.

[coveralls]

coverage: 92.49% (+0.1%) from 92.383% when pulling 9b04a8f on refactoring-SequenceMatcher into 6502a46 on master.