Minor changes to parser

The parser now lets the level zero indentation be determined by the
first non-empty non-commment line.  This will usually be the first
column, but this allows the user to indent the entire file and also
avoids an error in Parser.read when which would be caused otherwise if
the first line was considered level 1 instead of zero.

The parser also can be run as a program to read files and output the
result of Parser.read method.
Added ideas documentation