replace '[:blank:]' pattern with ' \t'
replace '[:alnum:]' pattern with 'a-zA-Z0-9'
replace '[:alpha:]' pattern with 'a-zA-Z'
replace '[[:digit:]]' pattern with '\d'
define constants for regexp character classes
Merge pull request #2 from mojavelinux/pr-668-review

Use constants for regexp character classes
Remove Struct in favor of Class
flatten any_list regexp to single line
Merge pull request #668 from Mogztter/opal-regexp
switch to RUBY_ENGINE_OPAL in conditional
set File::ALT_SEPARATOR in opal_ext/file
revert to Struct in cases supported by Opal
Merge pull request #675 from Mogztter/opal-struct
fix nested regex character class in Ruby 1.8
resolves #677 unescape escaped square closing bracket in footnote text
use appropriate loop when assigning header metadata to document
fix rowspan assignment for compatibility with Opal
minor optimization for partintro in docbook backend
fix while loop exit for Opal compatibility
remove sub of Set, define to_set properly