fix(emacs/lean-server): missing 'rx' at the beginning of regex
feat(library/data/int/basic): create alias for int.int
feat(library/hott): add 'path' namespace
feat(library/coercion): rename class to 'coercions'
feat(frontends/lean/pp): add 'pp.beta' option, closes #154
feat(shell): start 'lean --server' with 'pp.beta = true'
feat(library/coercion): add simple trick for defining coercions to function-class in a convenient way, closes #31
feat(frontends/lean/elaborator): use whnf in class-instance resolution, closes #160
feat(emacs/Cask): add Cask file

Close #92
feat(emacs/lean-require): check lean-mode dependencies in initialization

Close #91
doc(emacs/README.md): update required/optional packages
fix(frontends/lean/elaborator): whnf may produce assertion violation if term contains free variables
fix(frontends/lean/class): take whnf into account in add_instance
refactor(library): replace decidable_eq with abbreviation
chore(tests/lean): add untracked tests
fix(frontends/lean): OVERLOAD info for overloaded notation, fixes #132
feat(frontends/lean): add declaration to namespace without opening it, closes #161
refactor(library/logic/core/cast): cleanup
refactor(library/logic/core/eq): cleanup
fix(util/lean_path.cpp): get_exe_location follows symbolic link in OSX

Previously, we had different behaviors on Linux and OSX when
get_exe_location finds a location of executable:

 - Linux: follow symbolic link
 - OSX: not follow symbolic link