Pass all the C files in the project to CBMC

[prapicault]

To analyze non trivial applications, all the files being referred to from the analyzed function must be passed to CBMC.
There are several ways to address this:

• Give all the files from the current project (but this may be too big)
• Rely on CDT indexing capability to identify the files to analyze

[prapicault]

Initial version of this has been released where all the files are always taken. More work to come:

• Checkbox to enable this option
• Ability to select multiple files

[prapicault]

Improved UI now committed and binary pushed to bintray

[peterschrammel]

The detection of file types analysable by CBMC does not seem to work: currently also header files (and may be also others like object files etc) are passed to CBMC, which causes CBMC to fail with "failed to figure out type of file".