routine1: Process shape descriptor files
In jinyung/otolith: Identification of fish otolith using digital images

A wrapper function to do the routine of reading the files from imagej output (from runmacro) and combine the descriptor files into a single file.

1 2	routine1(imagejdir, write = TRUE, plot = FALSE, label = TRUE, extract = c(1, 6))

`imagejdir`	path of the folder containing the shape descriptor files. if not given, a GUI folder selector will prompt user to select (if run in Windows)
`write`	logical. whether to save a new file of combined descriptor.
`plot`	logical. whether to plot PCA for preliminary assessment of descriptor data. Only graphical output of first 3 PCs.
`label`	logical. Whether to extract label from the image file name.
`extract`	a numeric vector of two number telling which characters to extract from the file name to become the species name, if `label=TRUE`. The first is the starting position, second is the last position of character to extract.