Fixes #16850: Add config folder for customization files
Support including config file multiple times for custom_strings_inc.php
Update config_inc.php location in TestConfig
Update Travis to make config folder writable.
Changed chmod to be recursive for Travis.
Moved chmod to apply for all php versions not just 5.3.
Merged latest from master
Merged latest form master 2.
Rename all webservice configs options to webservice_* instead mc_*
Add support for MANTIS_CONFIG_FOLDER instead of MANTIS_CONFIG
Fixes with handling of global variables.
Fix include errors.
Relationship include fix.
Use config_get_global() for getting config_path in relationship_api.
Remove hard coded instances of config folder references
Fixed error where absolute_path was not defined.
Remove custom_strings_file config.
Updated checks page with config folder related updates.
Install page detects and complains about configs in old location.
Fixes #16850: Add config folder for customization files
Fixes #16446: Merge MantisConnect configs into MantisBT standard configs.

This change adds a config folder that includes all custom_*_inc.php files and config_inc.php file.

The SOAP API configs are now also merged into the standard configs. The fact that the separate configs was from the days where MantisConnect web service was separate from MantisBT. Now it is just confusing.

This change includes the addition of a configurable config path that can be set via an environment variable (MANTIS_CONFIG_FOLDER) or defaulted to MantisBT config subfolder. The change also includes all the necessary validation in admin/check/ and admin/install.php.

Conflicts:
	api/soap/mc_config_defaults_inc.php