Ascendex modifyMarginHelper, addMargin, reduceMargin
Ascendex modifyMarginHelper, addMargin, reduceMargin

Added methods that allow you to increase or decrease the margin on perpetual swaps for ascendex:
https://ascendex.github.io/ascendex-futures-pro-api-v2/#change-margin-for-isolated-positions
```
ascendex.addMargin (BTC/USDT:USDT, 1)
1462 ms
{
  info: { code: '0' },
  type: 'add',
  amount: '1',
  code: 'USDT',
  symbol: 'BTC/USDT:USDT',
  status: 'ok'
}
```

ccxt/ccxt,ccxt/ccxt,ccxt/ccxt,ccxt/ccxt,ccxt/ccxt