Cellular space (Has a CW-structure)

[felixpernegger]

Property Suggestion

A space is said to be cellular if it is induced by some CW structure.

Rationale

This is not a common property but CW-complexes are extremely common in algebraic topology and homotopy theory.
CW structures are likely discussed in every textbook about algebraic topology, in particular Hatcher chapter 0 discusses them.

https://en.wikipedia.org/wiki/CW_complex
(there is also a very short wikipedia entry on cellular spaces themselves, but this assumes compact also)

Relationship to other properties

See bottom of #1633 for some. Likely many more.
In particular, by Hatcher Prop. A.3 every cellular space is Hausdorff!

[prabau]

I am all for this. But can we please not implement this until we finish with locally simply connected and maybe locally contractible?