Rename operator to operation where ambiguous

We were calling everything we could push to the op-stack an operator,
which wasn't technically correct. For example, motions aren't operators.
This uses the more general term "operation" instead.
Add operator-pending mode
Delete inner word on `diw` keystroke
:lipstick: Extract ::pushOperations from ::handleCommands helper
Capitalize closure-scoped variables to prevent accidentally overwriting
Separate commands that always push operations from other commands

This way we *never* call ::pushOperations with non-operational values.
Apply block-cursor styling in .operator-pending-mode
Make 'iw' work in visual mode
Merge branch 'master' into ns-operator-pending

Conflicts:
	lib/operators.coffee
	lib/vim-state.coffee
Add CHANGELOG entry for operator-pending mode
:fire: some copy :spaghetti:
Merge pull request #183 from atom/ns-operator-pending

Implement operator pending mode and text objects