Risk parity and risk budgeting

Toolset alloc_parity: 3 tools.

Tool	What it does	Notes
`alloc_risk_parity`	Risk parity (equal risk contribution) or risk budgeting portfolio for one of 22 risk measures (standard deviation, MAD, CVaR, EVaR, CDaR, ulcer index, …): each asset’s share of portfolio risk matches its budget (equal, per asset, or equal per class).
`alloc_relaxed_risk_parity`	Relaxed risk parity on variance: risk contributions near their budgets while a minimum expected return or weight rules can bind, which exact risk parity cannot honour.
`alloc_factor_risk_budget`	Factor risk budgeting on a factor model of the assets: parity spreads portfolio risk across the factors by factor_budget for one of 22 risk measures; constrained optimises the objective on variance while each factor’s share of variance obeys factor_limits (and constraints).

Inputs, limits and outputs are described in Fincept Allocation. Full schemas: fincept_describe_tool.