Add multiple file upload functionality

Adds a new option in config_defaults_inc.php (file_upload_max_num) to
determine how many files can be simultaneously uploaded.

Modifies the code in issue reporting and view details pages, to enable
the new functionality.

Fixes #5228

Conflicts:

	bug_file_add.php
	config_defaults_inc.php
Fix whitespace and code alignment, removed useless code

Conflicts:

	bug_report.php
Add multi-file upload to bug reporting page

Fixes #5228

Conflicts:

	bug_report.php
	bug_report_page.php
I18l support for multi-file upload

Adds new strings to handle the plurals when uploading multiple files
(e.g. "Upload File" / "Upload Files") and conditionally display the
appropriate one depending on value of file_upload_max_num

Fixes #5228

Conflicts:

	bug_file_upload_inc.php
	bug_report_page.php
	lang/strings_english.txt
Remove duplicate error code and message

There were two separate error constants defined, ERROR_DUPLICATE_FILE
and ERROR_FILE_DUPLICATE, corresponding to an error message string with
identical text.

This commit removes the redundant constant ERROR_DUPLICATE_FILE and the
corresponding error message.

Fixes #5228

Conflicts:

	lang/strings_english.txt
Document g_file_upload_max_num in the administration guide

Affects #5228: Attaching multiple files in one go.
Make the crypto error message descriptive to reflect the minimum 16 character length.
Issue #14086: Default administrator timezone to server timezone. (partial fix).
Fixes #14013: System notice in bug_check_workflow().

If the status workflow is defined, but there is no corresponding entry to the current state, then allow all statuses.  The reasoning is that there should always be at least one possible next status.
Fixes #13993: Support search by email in manage users page
- Search by email, if no match by username.
- Use the label 'Search' instead of 'Username' for the text field.
Fixes #13994: Use rounded edges for avatars

Use CSS to make the gravatars have rounded edges.
Fix #13992: Use Gravatar generated patterns based on email hash for users wh

- Change gravatar integration to generate patterns based on email hash when
- Moved the checking for show_avatar inside the print_avatar() API.
- Remove default_avatar config option and delete the image.
Fixed documentation typo for column names

The field name for additional information is additional_info rather than additional_information.
Fixed #13740: Support auto-redirection from MantisBT to MantisTouch for mobi

1. Auto-detect mobile browser.
2. Redirect to a configured instance of MantisTouch, passing in the URL of t

This functionality will be controlled via a configuration option that enable
Added mobile_api.php which was missed from previous commit.
Fixed include for mobile_api.php
Fix utf8 offset when logging SQL in db_query_bound

The fix for #13280 (5835572fde9df4d0837f0105c6c44c75fe64c07c) only fixed
one part of the problem, i.e. when the UTF8 characters were in the SQL
query itself. This commit fixes the remaining case when the string
parameters contain multibyte chars.

Fixes #14097
Make index variable 0-based to optimize and make code more readable
Documentation update following obsoleted show_queries_list

See 3ea2997ae1b2c70055dd276dc15ea8f6337ca50b