[BUGFIX] Support edge-case URLs of secondary Asset files

For example, an URL like `/file.css?#iefix` would cause an error when attempting to copy the file `/file.css` which you have invalid chars appended to the name.

Fixes: #216
[TASK] Support relative secondary Asset files in inline CSS
[TASK] Shorten regular expression for detecting file names
Merge pull request #232 from NamelessCoder/regexfilename

[BUGFIX] Support edge-case URLs of secondary Asset files
[BUGFIX] Correct destination path for copying assets

Destination path for assets was based on the full css path including the filename.
Merge pull request #234 from bjo3rnf/assetpathfix

[BUGFIX] Correct destination path for copying assets
[BUGFIX] Use provided variables' checksum as name part

Before: only when `fluid="TRUE"` would the variables be considered.

After: if `arguments` is filled with any value, variables are considered and will add a uniqueness checksum to the Asset filename.

Fixes: #210
[DOC] Change description of argument `arguments` on Assets
Merge pull request #235 from NamelessCoder/assetvariableschecksum

[BUGFIX] Use provided variables' checksum as name part