(defendant received gift of land with stipulation that defendant could develop land for “agricultural, academic, research and development, delivery of health and medical care and services, or related purposes” or that the defendant’s proposed “mixed-use” research park would use land entirely for such purposes; plaintiffs, family members of deceased donor, argued that defendant’s plans for land violated terms of agreement due to scale, density and lessor/lessee structure of defendant’s plans; court determined that donor agreement not ambiguous and extrinsic evidence need not be considered; defendant’s plans for land permissible under donor agreement).