Fixed spelling issue refering to pip installer

Thanks to Gunther Cox for pointing out this error.
Added 'Clear Text' keyword for clearing the text value of a text entry element.
Added 'Locator Should Match X Times' keyword similar and more generic version of 'Xpath Should Match X Times' keyword and test.
Added test for new 'Clear Text' keyword.
add method _find_element_by_partial_text
QAR-48273: Fixed build failure caused by extra content in output.xml
QAR-48273: Applied fix for 'Choose File' bug, from Helio Guilherme (532295cbce)
QAR-48165: Added support for negative indexes in Robot keywords
QAR-48165: Added tests for negative indexes, tidied code
QAR-48165: Removed unnecessary import of jQuery
Merge pull request #1 from eweitz/negative-index

Support for negative indexes in Robot keywords
add links to INSTALL and BUILD files
Merge pull request #317 from eweitz/fixed-se2lib-build

Fixed build, applied fix for 'Choose File' bug, from Hélio Guilherme, and added support for negative indexes in Robot keywords
Merge pull request #318 from laurentbristiel/master

add links to INSTALL and BUILD files
doc updates related to loglevels and logging
fixes #253
fix JavaScript kw doc
log level trace not supported
Merge pull request #320 from ombre42/misc-doc

Misc doc updates
Moved 'Locator Should Match X Times' acceptance test.

Moved test from test/acceptance/keywords/elements.txt to
test/acceptance/keywords/content_assertions.txt.