There shall be a board of library trustees which shall consist of nine (9) members elected for terms of three years each, so arranged that the term of office as nearly an equal number of members as is possible shall expire each year. The board of library trustees shall have general charge of the care and management of the town library, and of all property of the town relating thereto, in consultation with the Town Manager. The board of library trustees shall have all of the powers and duties which are given to library trustees under the constitution and laws of the Commonwealth of Massachusetts and shall have such additional powers and duties as may be authorized by the charter, by by-law or by other vote of the town meeting.