Add Colors to compile

[martindsouza]

See http://orasql.org/2013/05/22/sqlplus-tips-6-colorizing-output/

Example of how I used it:

set define off
--
<compile file>
--
set define on
@$SQL_FILE_COLOR
prompt &_C_RED
show errors
prompt &_C_RESET
exit;

Not sure if when running compile.sql you could reference colors.sql or if the path would come into play. Note colors.sql has some hidden characters so its important to include it as is (see blog post for file contents)