This patch enables math expression evaluation for most of the text input
controls in pcbnew.
NEW: pcbnew text input controls are able to evaluate simple
mathematical expressions, including distance units (e.g. 5.0+(2*1.2mm)).
Since reference and value are not anymore always on silk changed the label on the corresponding options in the plot dialog
The 'proper Gerber extensions' was renamed in dialog as 'Protel Gerberl extensions': I don't know if it was a typo/misunderstanding or what but the proper extension is gbr; the set of alternative extensions seems to be the one used by Protel/Altium.
File "rules" has instructional text as comments near top.
2) Convert all text files in repo to LF line ending form.
Any checkout done with "rules" in play will convert the working
tree to native line ending, while keeping repo as LF line ending.