Parses a column header equivalent to the regexp:
\s*:\s*[delimiterChar]+\s*:\s*
public static bool ParseColumnHeader(ref StringSlice slice, char delimiterChar, scoped out TableColumnAlign? align, scoped out int delimiterCount)
The text slice.
The delimiter character (either - or =).
The alignment of the column.
The number of delimiters.
true if parsing was successful