Add a `DEFAULT_CONFIG_PATH` and ConfigSettings::readSetting(char*) scaffold

This will serve as the API to populate the settings from
a file on disk before evaulating command line arguments.
A simple key=value config parser

With comments
Whitespace.
_trim_string() is now TRIM_STRING() the macro
Centralize settings concerns in settings.cpp/h
Fail a config read if we can't read it instead of setting 0 settings
Add -c <config> option to read a non-default config
Actually fail the read if a key is unknown
Merge pull request #55 from sshirokov/config-file

Support for loading Configuration Files
Define a multiline separator
WIP: Bunch out output around a multiline parser
Split TRIM_STRING into LTRIMS_STRING and RTRIM_STRING
Whitespace trim before I start hacking.
ConfigSettings::[start|end]Code are now std::string
Config support for multiline strings.

Multiline strings are started with """
and continue until a line contains only """ at the beginning

For example:

```
# Start and End gcode
startCode = """
; This is coming from the config
"""

endCode = """
;     such end code
;

; very wow
"""
```
No need for iostream, I guess.
Add raft for wipe tower. https://github.com/daid/Cura/issues/725
Merge branch 'master' of github.com:Ultimaker/CuraEngine
Merge pull request #56 from sshirokov/multiline-config

Multiline configuration values
Add support for line based support material.