Issue 5164: Allow capital E in scientific notation

[rdeforest]

• Fixes Bug: Scientific notation should allow uppercase E #5164
• Remove error for capital E from lexer
• Change tests to match

[GeoffreyBooth]

The code looks fine, anyone have opinions on whether we should allow this change?

[edemaine]

My intuition/recollection is that "E" is more popular than "e" in scientific communities, so I'd lean toward allowing it. To confirm my feeling, here's some evidence:

• https://en.wikipedia.org/wiki/Scientific_notation#E-notation says "6.022E23 (or 6.022e23)", suggesting E is more common.
• Various educational websites seem to use "E" exclusively: https://www.mathsisfun.com/numbers/scientific-notation.html, https://chortle.ccsu.edu/Java5/Notes/chap11/ch11_5.html, https://www.nyu.edu/pages/mathmol/textbook/scinot.html

Of course, most other languages also support both e and E -- for example Python, though Python also supports 0O, so maybe not the best example.

[STRd6]

JavaScript allows capital E these days: https://tc39.es/ecma262/multipage/ecmascript-language-lexical-grammar.html#prod-ExponentIndicator