add hex formatting options to frontmatter

[backwardspy]

it'd be nice to be able to configure how whiskers represents colour as hexadecimal.

for example, this template:

---
whiskers:
  hex:
    capitalize: true
    prefix: "#"
---
{red.hex}

would produce #D20F39 instead of the default d20f39.

capitalize + prefix as options gives us a good amount of flexibility out of the box for common formats like #RRGGBB and 0xRRGGBB, but it's worth considering a more complex implementation that could allow more control, for example being able to specify a format string like 0x{a:02X}{b:02X}{g:02X}{r:02X} to produce 0xAABBGGRR format colours.

[rubyowo]

i assume you mean 0x{a:02X}{b:02X}{g:02X}{r:02X}

[backwardspy]

i assume you mean 0x{a:02X}{b:02X}{g:02X}{r:02X}

ah yep, good catch! edited.

[backwardspy]

@rubyowo has rightly pointed out that we already have some of this implemented, but it's undocumented. i would advise not relying on the frontmatter options in their current form as we might change then, but if they solve a big problem right now then they are technically usable.

[backwardspy]

completed in #18