Handle multiple words research

[fpagnoux]

As a legislation explorer user typing "salaire base" in the search field, I get the variable "salaire_de_base" in my results

[MattiSG]

Should supersede #55 if parameters are properly named.

[MattiSG]

1. Select only variables where name contains each query words in either variable name or description.
2. Group variables according to query word match count in variable name and order them in decreasing order.
3. Group each subset according to query word match index sum and sort them in increasing order.
4. Sort each sub-sub-subset according to alphabetical order.
5. Concatenate all sub-sub-subsets and present them as ordered results list.

Examples

salaire base →

• salaire_de_base Salaire de base, en général appelé salaire brut, la 1ère ligne sur la fiche de paie
• cotsoc.indemnite_fin_contrat.taux Pourcentage du salaire de base

crds →

• crds Contributions au remboursement de la dette sociale
• crds_cap_bar CRDS sur les revenus du capital soumis au barème
• …

[sandcha]

1 => Every result must cover all query words ; remove results that doesn't.

Besides, query word repetition in a variable/parameter name and description has no influence ; do not change the order/weight of such results.