EODHD common class

[LouisSzeto]

Description

Add EODHD class for abstraction of EODHD datasets for their economic events, macro indicators, etc.

Related Issue

NA

Motivation and Context

Since we cannot share the EODHD class across 2 dlls, it is added to LEAN.

Requires Documentation Change

NA

How Has This Been Tested?

No test needed, since they are just static strings.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• Refactor (non-breaking change which improves implementation)
• Performance (non-breaking change which improves performance. Please add associated performance test and results)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Non-functional change (xml comments/documentation/etc)

Checklist:

• My code follows the code style of this project.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
  no test needed
• All new and existing tests passed.
• My branch follows the naming convention bug-<issue#>-<description> or feature-<issue#>-<description>