convex_function generalized

[mkerjean]

Motivation for this change

Generalization the definition of convex functions in convex.v, from a function f: R -> R^o for R: realType to a function f : E -> R^o, for R: numFieldType and E : convex_lmodType.

This will allow the use of convex_function in the statement of Hahn-Banach theorem, and more generally, the use of semi-norms as convex functions on instances of convextvsType.

Co-authored-by: Reynald Affeldt reynald.affeldt@aist.go.jp

Checklist

• added corresponding entries in CHANGELOG_UNRELEASED.md

• added corresponding documentation in the headers

Reference: How to document

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