Tradingview chart - 15 sec marker issue

**Describe the bug**

1. 15 second marker turns TV chart 'grey' (dull); Consider removing from options (realistically responsive?)
2. Consider adding 15 minute, 30 minute,2hr and/or 4hr markers

**To Reproduce**
Steps to reproduce the behavior:
1. Go toExchange at staging.bitshares.org
2. Click on 15 sec marker
3. See error in red circles
Attached for color comparison to illustrate the point

**Expected behavior**
Chart to respond to selected marker

**Desktop (please complete the following information):**
- OS: Windows 8.1
- Browser Opera
- Version 64.0.3417.73

**Additional comments**
RC bitshares 3.1.191011 there are 7 markers (1m, 5m, 15m, 30m, 1hr, 4hr, 1d). All are responsive.

Start at the Exchange view on staging.bitshares.org and reproduce the reported behavior by selecting the 15 sec marker in the TradingView chart. Compare it with the responsive markers listed in the issue and verify the chart's behavior after a selection; the requested additional intervals and possible removal of 15 sec need clarification before implementation.

Written by the indexing model from the issue text.