Scientific notation clashes with implicit multiplication

[Pol Welter]

The tokenizer is designed to ignore spaces in numbers. This is usually a good thing. However it will also make things like this fail:

eps = 10

2 eps 
INVALID EXPRESSION

Any variable or function that starts with the letter e will break implied multiplication.

[Helder Correia]

Fixed issue #599. Rollback the parsing if an invalid character is found while parsing the start of the exponent part.

→ <<cset 383cf6a2b2fd>>