Don't parse `1.` in `1..10` as float

[brianrourkeboll]

• Use a negative lookahead to avoid treating the first . in the range operator .. as part of a floating point literal in expressions like 1..10, 1..10..100.
• Add more range & slicing examples to sample code.

let numbers = [1 .. 10]
let numbers = [1..10]                   // Now parsed correctly.
let numbers = [1 .. 10 .. 100]
let numbers = [1..10..100]              // Now parsed correctly.
let numbers = [1.0 .. 10.0]
let numbers = [1.0..10.0]
let numbers = [1.0 .. 10.0 .. 100.0]
let numbers = [1.0..10.0..100.0]
let numbers = numbers[1 ..]
let numbers = numbers[1..]              // Now parsed correctly.
let numbers = numbers[1 .. 10]
let numbers = numbers[1..10]            // Now parsed correctly.
let numbers = numbers[.. 10]
let numbers = numbers[..10]

Before

GitHub[^1]

Visual Studio Code with Ionide

(Font with ligatures)

(Font without ligatures)

After

Visual Studio Code with Ionide

(Font with ligatures)

(Font without ligatures)

[^1]: Which uses this grammar.

[baronfel]

I love it - thank you for this change. Do you have an 'after' screenshot that you could drop here for posterity?

[brianrourkeboll]

@baronfel Updated the description.

[baronfel]

Wonderful, thank you! Happy to merge this, and looking forward to shipping it in the next version of Ionide.