[Change] estimateBetas: overnight returns are mapped through Id to avoid duplication

Signed-off-by: Oleg Komarov <o.komarov11@imperial.ac.uk>
[Change/Fix] ismemberb: use updated version

Signed-off-by: Oleg Komarov <o.komarov11@imperial.ac.uk>
[Minor]

Signed-off-by: Oleg Komarov <o.komarov11@imperial.ac.uk>
Merge branch 'master' of git@github.com:okomarov/HFbetas.git