Updates to scripting and reports for CPA macro functionality

[sjanzou]

Changes

casewin - add ExportCasflowExcel
reports - fix multiple table header lines
script - add fcall_export_cashflow_excel
macro - include invoke.h
results - move Export from private to public

Easiest way to test is to

1. copy the deploy/runtime/macros/Community Solar/Community Power Accelerator.lk macro over to this branch (but do not commit)
2. copy the deploy/runtime/quickstart/CPA-CommunitySolar.samreport report template (but do not commit)
3. create a PVWatts/Community solar case
4. run the Community Power Accelerator macro
5. Check that the cash flow exports and the pdf report has a 2-line column header

[cpaulgilman]

For LK function export_cashflow_excel():

1. Function returns Null instead of boolean:

2. For PVWatts / No Financial case, function opens empty Excel file. For configs with no financial model, I think it should return False and not open Excel.

3. The function runs a simulation, which means that in some cases (like the CPA macros) it runs a simulation when there are already results. It might be best to a) not run a simulation and return a message if there are no results, or b) add a flag parameter that determines whether to run a simulation.

4. In Linux, the function runs and returns Null. I think it should return False.

5. What is the "page name" input parameter?

6. After opening Excel, the function displays the SAM Results window. I think that should be left to the script writer: If they want to display a page, they can use show_page() after calling the function.

[sjanzou]

With commit 0a4b9c0, the fcall_export_cashflow_excel performs as follows:

1. always returns a boolean
2. no case - returns 0 (false from script)

3. case with no financial model - returns 0 (false from script) 4. case not yet run - returns 0 (false from script) 5. after base case run - returns 1 (true from script)

[cpaulgilman]

Thanks @sjanzou. I made some additional changes based on your updates. I think this looks good now.