[Issue #17] Moved pom.xml

Moved the test purposes pom.xml into tests subdirectory.
issue 8: fix display of ASCII art regression

regression was introduced by refacto of silent mode, jirac_echo can not be used directly
test silend_mode variable directly in ASCII art methods
improve jirac_echo(): support any number of parameter

all parameters are forwarded to the echo command
ISSUE #9: use name if available in pom.xml, otherwise artifactId

factorise code retrieving the text of an XML node in a pom.xml file
modify xml parser command to support non existing node without displaying a warning message, works with xmlstartlet, must be tested under mac
Issue #15. Switch to MIT License.
[#12]remove extra line

Remove return at beginning of generated comment
[#2] implement option --standard-output

--standard-output option enables silent mode automatically, requires either option --number or option --grep and print generated comment to the standard output
also:
 - minor fix in help of --number option
 - add default values for all variables initialized from command arguments
 - minor indent fixes in ui_functions.sh
[#2] remove description override in print-mode 0

this functionnality makes print-mode 0 non pipable, it was not used, so it was decided to remove it