Release 1.0.18

Fix Incorrect Function Behavior: ISBLANK

• Issue #22

New Function Support: ENCODEURL, WEBSERVICE

• WEBSERVICE is not implemented for Node.js due to extra dependency requires.

const FormulaParser = require('fast-formula-parser');
const {FormulaHelpers: H, Types} = FormulaParser;

// To use WEBSERVICE in Node.js, please override this function: 
new FormulaParser({
    functionsNeedContext: {
        WEBSERVICE: (context, url) => {
           const fetch = require('node-fetch');
           url = H.accept(url, Types.STRING);
           return fetch(url).then(res => res.text());
    }}
})