Change from Apache to BSD 3-clause license

[paulf81]

Change from Apache to BSD license

This pull request starts the process of switching from APACHE to BSD license. Specifically the 3-clause BSD license as used in OpenOA So far:

• Updated the License.txt file (based on https://github.com/NREL/OpenOA/blob/ef63a61ed88f1e71816a5e89e2b7f3904b5d0227/LICENSE.txt)
• Updated setup.py
• Updates README.md
• Removes the header block of commented code at the start of each file (see @RHammond2 's comment below) for consistency with other codes/common practice

[RHammond2]

@paulf81, this is something that might be required of some specific licenses (definitely not the BSD 3 Clause though), but is generally a relic of old practices. You can certainly add the license to each file if you feel that would be helpful to users making new models/code from FLORIS, but it's not at all required.

[paulf81]

@paulf81, this is something that might be required of some specific licenses (definitely not the BSD 3 Clause though), but is generally a relic of old practices. You can certainly add the license to each file if you feel that would be helpful to users making new models/code from FLORIS, but it's not at all required.

Thank you @RHammond2 !

[paulf81]

@rafmudaf and @misi9170 this is ready for review

[rafmudaf]

For module files and scripts, I think we should commit to the convention of having one blank line at the beginning of the file, then any imports, and then multiline comments:

import this
import that

"""
This is what this example does...
"""

fi = FlorisInterface("file")
fi.many_wind_energies()

@paulf81 if you agree, I'll make these changes.

[paulf81]

For module files and scripts, I think we should commit to the convention of having one blank line at the beginning of the file, then any imports, and then multiline comments:

import this
import that

"""
This is what this example does...
"""

fi = FlorisInterface("file")
fi.many_wind_energies()

@paulf81 if you agree, I'll make these changes.

Sounds great to me @rafmudaf thank you