create simple "essential run inspection" plots Rmarkdown file

[japhir]

base it on the inspecting_clumped-processing.Rmd notebook
take only the plots that are essential,

• inspect the scans: min_47 vs. scan_datetime
• initial intensities: s44_init and r44_init vs file_datetime
• d13C_PDB_mean vs file_datetime
• d18O_PDB_mean vs file_datetime
• D47_raw_mean vs file_datetime
• standard deviations?
• offset corrections
• ETFs