AMM design

[kayabaNerve]

I believe the main question would be if we want to support a Uniswap v2 or v3-esque model. The latter would have increased internal complexity, yet offer functionality such as effective limit orders and greater LP-control over their positions. It would also naturally have a more complicated API we may not be interested in presenting to users.

The questions become:

• Implementation complexity
• Natural API complexity
• Side effects of concentrated liquidity on the overall economy
• Hybrid designs, such as fully symmetric liquidity providing, yet still offering limit orders (the one exception)

Related to #58, and potentially should be merged under it.

[kayabaNerve]

For now, the simpler symmetric design will be used. Once we have that, we can consider moving to a v3-esque model.

[kayabaNerve]

Closing this for a later CLP-evolution issue, since it seems most likely we'll launch with full-range liquidity.

[kayabaNerve]

#420