Institutions, Accounts and Categories views fixes

• refactors/renames the interchangeably used "sort code" and "routing number" into culture-agnostic "bank code". Note that the XML/DB storage fields/columns are left intact for backwards compatibility.
• uses AccountsModel::Column enum in InstitutionsModel. This is to avoid duplication of enums, especially that InstitutionsModel already uses the headerData() of AccountsModel, so the enum numeric values of columns must match unconditionally.
• hides columns that do not pertain to specific views
• adds tooltips to columns
• adds missing columns (IBAN, SWIFT/BIC)
• fixes a bug where IBAN was shown in "Sort Code" column
• adds tooltips to New Institution Wizard
• improves documentation around Bank Code.
• refactors KNewBankDlg into KNewInstitutionDlg for consistency