fmt! does not support %e

[auroranockert]

%e should work like in printf in C, it should format a floating-point number using scientific notation.

[graydon]

Still legit: #8245 while extremely promising does not contain any logic for formatting floats at all yet. Will need to pick that up. Nominating for feature complete, while I'm here.

[catamorphism]

Accepted for feature-complete