Fix #2406 query builder cache

Signed-off-by: GDmac <grdalenoort@gmail.com>
docs: get_compile_select

get_compile_select(null,false) without reset also preserves LIMIT settings
Merge branch 'develop' of https://github.com/EllisLab/CodeIgniter into develop
Cleanup PR #2719

for Fix #2406 query builder cache

Signed-off-by: GDmac <grdalenoort@gmail.com>
Merge pull request #2719 from GDmac/develop

Fix #2406 query builder cache
[ci skip] Remove some whitespace chars
Deprecate CI_Input::is_cli_request() and add common function is_cli() to replace it

Calls to this function are often needed before the Input library is available
Add CLI error templates and only send HTTP status headers for non-CLI requests (issue #1743)
Update the upgrade instructions for error templates