input scenario writer

[ahobeost]

A writer, which simplifies the definition of optimization problems, will simplify calls to optihood by other softwares.
Preferably, this writer would provide the following:

• an initial file to populate
• the option to update values in an existing file

[ahobeost]

Based on the existing code, the "createScenario" functionality could return the "excelData" before writing it to file.
This would allow the program to adjust the values before writing.

Within the existing code this could look as follows:

• parse config
• prep excel data
• write to file

The desired writer could then do the following:
first time:

• parse config
• prep excel data
• adjust excel data
• write to file

all subsequent times:

• read excel data
• adjust excel data
• overwrite file