Improve exceptions and error messages

[HebaruSan]

netkan.exe's error outputs are not always as clear as they could be. In some cases important details of the error are omitted, and very rarely a sentence is simply unclear.

This code change updates the following error strings to help with investigating issues.

Error	Change
JSON deserialization error	Add the Exception.Message property produced by PopulateObject
Install stanzas must have a file an install_to	Remove "a file" since it looks non-grammatical
Could not get the mod from SD, reason: {upstream error}.	Change SD to SpaceDock, remove trailing period
Expanding {url} to full SD URL	Change SD to SpaceDock
Could not normalize URL: {non URL}	Add mod identifier
Could not match version with find pattern	Add the version and the find pattern
Module contains no files to install.	Explain the install stanzas that did not match rather than suggesting the download is empty