v0.7.49

• Removed the ten-state limit on undo history in the web UI. Undo states are now discarded only when their restore data exceeds the storage limit.
• The web UI's right-click menu now stays open after copying a value, so several values can be copied from the same point.
• The web UI's right-click menu now reports the band values of the raster pixel under the cursor, plus a color tile and hex value for color images.
• -blur now accepts a real-world distance as well as a pixel count (e.g. -blur 500m), takes its radius as a bare argument (e.g. -blur 5px), and appears in the command list printed by mapshaper -h.
• Added -contours command for tracing contour lines from a raster layer, with interval=, levels=, base=, band= and field= options. Traced lines are smoothed at an auto-selected one-pixel interval; use no-smoothing to skip that step.
• Added -i raster-type=continuous for measurement rasters like elevation models, which use bilinear resampling but keep the source nodata value instead of a fill color when projected (ordinarily the correct type should be auto-detected).
• Fixed loss of precision when projecting a floating point raster: bilinear resampling was rounding every sample to a whole number.
• Fixed bilinear resampling averaging nodata samples together with real values along the edges of a raster's valid data.