Provide more information to errors

[egraether]

• show translation unit of error
• make whole translation unit available after preprocessor
• provide chronic list of included header files

[egraether]

Provide full command line information of translation unit as separate column in errors table with 2017.2.75

[egraether]

Removed translation unit information from errors again with 2018.1., because it greatly increased DB size. Providing better help information on error fixing since 2017.4.46. Closing this for now, awaiting new feedback on the matter.