pass some tests based on indent as symbol

pass some tests on parsing indent/undent/newline symbol
parser.clause, colon lead some clauses
half dent and half undent, if-then-else

add half dent and half undent, pass some tests
pass two tests on if-then-else statement.
statement as clause, : and indent can not be first item of clauses.

statement is clause, and matched at first
"if 1 then if 2 then 3" pass test
: and indent can not be first token of clause, so that clause can one callable.
parse if-then-else according to whether the statement is at head of line.

parse embedding if-then-else statement, according to whether the statement is at head of line.
try-catch-else-finally

try-catch-else-finally pass tests that is copied and modified from if statement tests.
switch statement

switch statement pass some tests
rewrite try-catch-else-finally and its tests, all passed.
parse non interpolated string

parse raw and escape non interpolated string, pass 6 tests.