Log Message:
tex-l3{kernel,packages,experimental}{,-doc}: update to 2017.45340

- Rename \box_use_clear:N to \box_use_drop:N as this command has
  non-standard grouping behaviour
- New \inteval command in xfp
- New \c_catcode_active_space_tl
- Fix bug with color code when \current at color is not a simple
  string
- Fix behaviour of \sys_rand_seed: in engines without the
  underlying random number primitives
- Allow only integer powers for negative bases in floating point
  expressions
- Various documentation improvements