[Idea] Cohort upgrades

[tgig]

Hi guys, we use Blazer for all our reporting and it's wonderful. I'm considering submitting a few PRs to support our need for expanded cohort triangle functionality. Let me know what you think of these:

1. Make 0's blank so the triangle is easier to read (this one is easy and I can submit the PR for it right away, see first image below)
2. Ability to right align the triangle (Which means ability to put actual Dates at top instead of just "Month 1/2/...", see second image below)
3. Roll-up rows at bottom (see second image below)
4. Ability to order data ASC (Perhaps with an optional flag in the /* cohort analysis */ comment? Also second image)
5. Color highlighting to distinguish new vs existing (second image)

[tgig]

Forgot one important thing. I also want to create an automatic chart to accompany cohorts. Something like below:

[tgig]

I put up 2 PRs #461 #462 and am queueing more up in my own fork. I don't want to overwhelm the repo with a bunch of pulls if you're not into these mods, but let me know if I should keep sending them in...

[tgig]

Quick update, in case anybody is interested, seems like this repo is unattended these days.

I am mostly finished with my changes. Here's a preview of different styles of cohorts using the movielens database (which isn't a perfect fit for cohorts, but works well enough):

Right aligned, grouped by quarter

Left aligned, grouped by quarter

Right aligned, sum of values (e.g. for order value)

Left aligned, sum of values